- Email: [email protected]
Selective sentinel lymph node dissection in head and neck cutaneous melanoma
Operative Techniques in Otolaryngology (2013) 24, 13-18
Selective sentinel lymph node dissection in head and neck cutaneous melanoma Rogerio Izar Neves, MD, PhD, FACS From the Division of Plastic Surgery, Department of Surgery, Penn State Hershey Melanoma Center, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania. KEYWORDS Melanoma; Skin cancer; Sentinel lymph node; Surgery; Head and neck surgery
Sentinel lymph node biopsy accuracy and prognostic value in the head and neck region has been established. The article describes the current indications for the procedure, lymph node localization using lymphoscintigraphy and intra-operative blue dye injection, the surgical technique, and important recommendations to avoid complications in this very important anatomic region. © 2013 Elsevier Inc. All rights reserved.
Evolution of elective node dissections to sentinel lymph node biopsy; lymphoscintigraphy and technique O’Brien et al1 described the anatomically predicted drainage pattern of the head and neck in the hope that this would help guide more appropriate lymphadenectomies for head and neck cancers. Through clinical observation and the implementation of lymphoscintigraphy, the complexities of head and neck lymphatic drainage are better recognized, thus proving such models as O’Brien’s unreliable. Historically, occult metastases of head and neck melanomas were identified through elective node dissections. Factors such as tumor thickness, mitotic rate, ulceration, and anatomic location are known to be prognostic indicators, particularly with tumor staging.2 First described by Morton et al in 1992, sentinel lymph node biopsy (SLNB) has become a common staging procedure for cutaneous melanoma.3,4 Accurately predicting the status of the regional lymph node basin, a positive SLNB identifies a subset of patients who may benefit from com-
Address reprint requests and correspondence: Rogerio Izar Neves, MD, PhD, FACS, Division of Plastic Surgery, Department of Surgery, Penn State Hershey Melanoma Center, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, 500 University Drive, H071 PO. Box 850, Hershey, PA 17033-0850. E-mail address: [email protected]. 1043-1810/$ -see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.otot.2012.12.005
pletion lymphadenectomy and are candidates for adjuvant therapy and/or clinical trials. Proximity of cranial nerves and ambiguous lymphatic drainage pose unique challenges to performing the SLNB procedure in the head and neck region.1,5,6 Two large series (n ⫽ 3897) have demonstrated higher recurrence rates in previously mapped negative nodal basins in the head and neck region relative to other anatomic regions, suggesting inferior SLNB accuracy.7,8 For long time, consistent correlation between SLNB status and overall survival was lacking in head and neck melanoma series.9-11 Despite the general adoption of SLNB for extremity and truncal cutaneous melanoma, debate around SLNB accuracy and prognostic value in the head and neck region remained until Erman et al11 published one of the largest single-institution series of head and neck melanoma patients demonstrating that SLNB accuracy and prognostic value in the head and neck region are indeed comparable with other sites. Preoperative lymphoscintigraphy is required to define the regional lymph basin(s) that drain the primary site; to localize the predominant drainage channels leading to the basin(s); and to localize the number of sentinel lymph nodes (SLNs) within the basin(s) draining through separate lymphatic channels. The radiocolloid to be used will not be specified, as many agents are in common use. The radiocolloid in common use at our center is the sulfur-colloid injected intradermally on 4 sides of the primary or previous site of the primary tumor. The SLNs are marked externally on the skin of the subject. Dynamic lymphoscintigraphy is
14
Operative Techniques in Otolaryngology, Vol 24, No 1, March 2013
performed within 1 day of the wide excision and selective lymph node dissection, with initial images at 30-45 minutes and delayed images at 1-2 hours. If 2 or more regional lymph node basins are identified by lymphoscintigraphy, intraoperative lymphatic mapping and selective lymph node dissection will be performed on both lymph node groups, as it has not been possible to predict which nodal group would be the site of metastases.
Lymphatic mapping and selective sentinel lymphadenectomy The current indication for lymphatic mapping and SLNB at the Penn State Hershey Melanoma Center are as follows: ●
● ● ● ●
Recommended for primary melanomas with Breslow ⬎1 mm; offered for primary melanomas with Breslow 0.76-1 mm Clark ⱖIV without clinically detected lymph node metastasis Mitotic rate ⱖ1 Presence of ulceration We discuss and may offer the procedure for selected patients with primary melanomas with Breslow ⬍0.76 mm if young (ⱕ45 years), with ulceration or mitotic rate ⬎1; or in those patients with extensive regression (ⱖ75%)
Patients undergo preoperative lymphoscintigraphy to identify the regional lymph basin at risk for metastases, and the radioactive individual lymph nodes should have the site of the SLN identified by markings on the skin. At the time of the surgical procedure, the patient should be positioned for easy access to the regional lymph node basin. They are usually positioned supine for melanomas on the head and neck. Patients with primary melanomas arising on the upper extremities or back should be positioned in the lateral decubitus for access to the axillary or posterior cervical lymph basins. Lymphatic mapping with the blue dye is performed before wide local excision. In the head and neck region, 0.5-1.0 mL of isosulfan blue is injected intradermally with a 30-gauge needle around the site of the primary lesion or incision biopsy. After massage of the area for approximately 5 minutes, incision should be performed. In case a delay occurs beyond 30-45 minutes for any reason, reinjection should be performed due to a dye “washout”12 (Figure 1). An incision is made in the regional lymph basin of the expected lymphatic drainage, over the site of the SLN marked by preoperative lymphoscintigraphy and the operating gamma probe “hot” spot, and the incision is oriented for inclusion within a complete lymphadenectomy incision (Figure 2). Incision of approximately 3 cm may be adequate in most cases—larger incisions should be used without reservation if improved exposure will diminish the risk of complication such as nerve injury (Figure 3).
Figure 1 In the head and neck region, 0.5-1.0 mL of isosulfan blue is injected intradermally with a 30-gauge needle around the site of the primary lesion or incision biopsy. After approximately 5-10 minutes, incision should be performed. (Color version of figure is available online.)
Once the incision over the SLN has been made, usually an afferent blue lymphatic channel is found, which leads to the blue-stained node(s) (Figure 4). Careful exploration of the surrounding tissue is necessary to identify any additional nodes and to distinguish them from the SLN(s). Special care needs to be taken in the selective dissection of SLNs in the parotid or spinal accessory nerve area. A nerve stimulator is helpful to guide the dissection to avoid nerve injury. Dissect the lymph node from the surrounding tissue bed. Dissection is facilitated by grasping the tissue adjacent the node (not the node itself), to not crush or tear the lymph node (Figure 5). The probe is used to help identify the SLN. Nodes are labeled as “hot” in vivo if they are 3-fold or ex vivo if they are 6-fold more radioactive than background counts around the basin. Radioactive counts of the lymph node basin are taken once the nodes are removed to determine if any additional radioactive nodes are present (Figure 6).
Neves
Selective Sentinel Lymph Node Dissection
If so, these are excised even if not blue and are labeled as SLNs that are “hot, not blue,” if not colored by the dye mixture. The hot node-to-background ratio will vary depending on the particular radiocolloid used by the institution, as well as the number of hot nodes. Other radioactive nodes do not need to be removed if early lymphoscintigraphic images indicate these are not sentinel nodes but second echelon nodes because they are not directly connected to the primary site by a lymphatic channel. In this case, they are likely to be second echelon nodes or those even further down the drainage pathway. The single-photon emission computed tomography with computed tomography is helpful and should be used when available. After removal of the lymph node, take and record 2 more counts. Once the wound bed reading drops below 10% of ex-vivo reading, you have successfully removed the SLNs (Figure 7). Intraoperative frozen sections for SLNs are not recommended. However, the specimen should be sent immediately to pathology. Once it has been determined that the basin contains no additional “hot” or “blue” nodes, the deep
15
Figure 3 Incision of approximately 3 cm may be adequate in some cases—larger incisions should be used without reservation if improved exposure will diminish the risk of complication such as nerve injury. (Color version of figure is available online.)
and superficial fasciae are approximated in separate layers as per surgeon preference, and the subcutaneous tissue and skin are closed with absorbable suture. After changing gloves and instruments, the primary site is then widely excised. However, in head and neck melanomas, it is common to have the primary site close to the SLN, creating a strong “radioactive background” not allowing for an accurate SLN identification. In those cases, we perform the wide local excision first. The success of SLN biopsy depends on appropriate patient selection. Patients with palpable regional disease or distant metastasis are not candidates because additional prognostic information will not be gained.6,11 Additionally, patients who have had previous neck dissections or resection of the primary site with wide margins are not deemed candidates owing to lack of accuracy.
Figure 2 An incision is made in the regional lymph basin of the expected lymphatic drainage, over the site of the sentinel lymph node (SLN) marked by preoperative lymphoscintigraphy and the operating gamma probe “hot” spot, and the incision is oriented for inclusion within a complete lymphadenectomy incision. (Color version of figure is available online.)
Figure 4 Afferent blue lymphatic channel is found, which leads to the blue-stained node. (Color version of figure is available online.)
16
Operative Techniques in Otolaryngology, Vol 24, No 1, March 2013 tium, which can result in high background counts. This not only makes probe-guided localization difficult, but it also can mask the presence of positive SLNs in the parotid.13,14 Lower doses of radioactive tracer may be used to partially overcome this.
Intraparotid SLN mapping Primary tumors located on the ear, the cheek, the forehead, and anterior scalp commonly have lymphatic drainage through the parotid gland. SLNB of intraparotid nodes has been a topic of some controversy owing to the potential morbidity encountered with damage to the facial nerve. Sentinel nodes in the parotid gland tend to be small (3-6 mm), are densely adherent to surrounding fibrofatty tissue, and are difficult to discretely localize by gamma probe.13,15,16 When available, the use of intra-operative nerve monitoring is recommended. However, Ollila and colleagues studied the accuracy, sensitivity, and morbidity of intraparotid SLN biopsies. Patients who were found to have metastases in the intraparotid SLNs then underwent a facial nerve sparing parotidectomy and modified radical neck dissection, and only 2.6% of the patients experienced temporary facial nerve palsy, which completely resolved. Likewise, Loree and colleagues demonstrated no facial nerve complications.14,17
Neck anatomy and neck dissection In performing any procedure on the head and neck, it is of the utmost importance to know the anatomy and where Figure 5 Careful exploration of the surrounding tissue is necessary to identify any additional nodes and to distinguish them from the SLN(s). Special care needs to be taken in the selective dissection of SLNs in the parotid or spinal accessory nerve area. A nerve stimulator is helpful to guide the dissection to avoid nerve injury. Dissect the lymph node from the surrounding tissue bed. Dissection is facilitated by grasping the tissue adjacent the node (not the node itself), to not crush or tear the lymph node. (Color version of figure is available online.)
Locating the SLNs intraoperatively requires aiming the gamma probe at the areas previously marked by lymphoscintigraphy and obtaining the maximum count on the gamma probe. After removal of hot and/or blue nodes, the tissue is then reassessed with the gamma probe. When the background is ⬍10% of the maximum probe counts, no nodes containing technetium are considered present. On removal of the SLNs, care must be taken to ensure the specimen is not damaged. Metastatic foci may be present at any location within the node. Inadvertent cutting through the capsule or excessive use of cautery can interfere with histologic evaluation of the SLN and small metastases can be missed. Another common problem encountered is with the parotid gland. The parotid gland takes up free techne-
Figure 6 Radioactive counts of the lymph node basin are taken once the nodes are removed to determine if any additional radioactive nodes are present.
Neves
Selective Sentinel Lymph Node Dissection
17 face, and ear, or demonstrate drainage to this site by lymphoscintigraphy. Pathologic examination of the SLN must be performed by assessment of permanent sections prepared from formalin-fixed and paraffin-embedded tissues. Lymph nodes should not undergo frozen section examinations. In many SLNs, the number of tumor cells is small and such cells may be present only in the immediate peri-meridional tissue, and the necessary preparative steps may entirely remove the diagnostic tissue, leading to a false-negative interpretation. This hazard is compounded by the fact that after frozen section analysis, the residual frozen tissue is thawed and placed in formalin fixative at room temperature, which may lead to further tissue distortion. When the fixed tissue is sectioned, it may be necessary again to cut away considerable potentially diagnostic tissue to achieve the desirable full-face sections that will include the critical subcapsular sinus. Frozen sections are always more difficult to interpret, and rapid immunohistochemistry on frozen tissue is usually less readily interpretable. When the node specimen is sent to pathology, the requisition form should state the number of nodes, the anatomic locations, the color as observed in the operating room, and the radioactivity for each node recorded. The pathology report should confirm the number of nodes submitted in the specimen to be sure adequate tissue had been taken. We recommend that SLNs be evaluated at multiple levels, using conventional hematoxylin and eosin staining and immunohistochemistry with antibodies to several melanoma marker epitopes. The lymph node should be cut in 2 halves through its longest meridian. The 2 halves are then placed cut-face down in cassettes and fixed for not less than 24 hours. Once a full-face section is obtained, 12 serial sections are removed, and sections 1, 3, 5, and 10 are stained with hematoxylin and eosin (H&E). Section 2 is stained for S-100 protein, section 4 is stained for HMB-45, and section 6 is stained for MART-1 (Melan-A). Sections 7, 8, and 9 are negative controls for the immunoperoxidase studies, and sections 10, 11, and 12 are used to repeat any study that is technically unsatisfactory or for additional immunohistochemistry. Our own experience is that this technique balances desirably extensive sampling with cost-effectiveness.
Figure 7 The probe is used to help identify the SLN. Nodes are labeled as “hot” in vivo if they are 3-fold or ex vivo if they are 6-fold more radioactive than background counts around the basin. After removal of the lymph node, take and record 2 more counts. Once the wound bed reading drops below 10% of ex-vivo reading, you have successfully removed the SLNs. (Color version of figure is available online.)
particular structures lie to decrease the chance of morbidity. The anatomy for a neck dissection will be described in another chapter in this volume. If a micrometastasis is found in the SLN, the patient should receive a completion lymph node dissection. A superficial parotidectomy is required to remove the parotid nodes for primaries that arise on the anterior scalp,
References 1. O’Brien CJ, Uren RF, Thompson JF, et al: Prediction of potential metastatic sites in cutaneous head and neck melanoma using lymphoscintigraphy. Am J Surg 170:461-466, 1995 2. Morton DL, Wen DR, Foshag LJ, et al: Intraoperative lymphatic mapping and selective cervical lymphadenectomy for early stage melanomas of the head and neck. J Clin Oncol 11:1751-1756, 1993 3. Morton DL, Wen DR, Wong JH, et al: Technical details of intraoperative lymphatic mapping for early stage melanoma. Arch Surg 127: 392-399, 1992 4. Balch CM, Gershenwald JE, Soong SJ, et al: Final version of 2009 AJCC melanoma staging and classification. J Clin Oncol 27:61996206, 2009 5. Willis AI, Ridge JA: Discordant lymphatic drainage patterns revealed by serial lymphoscintigraphy in cutaneous head and neck malignancies. Head Neck 29:979-985, 2007
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6. Morton DL, Cochran AJ, Thompson JF, et al: Sentinel node biopsy for early-stage melanoma: accuracy and morbidity in MSLT-I, an international multicenter trial. Ann Surg 242:302-311, 2005 7. Chao C, Wong SL, Edwards MJ, et al: Sentinel lymph node biopsy for head and neck melanomas. Ann Surg Oncol 10:21-26, 2003 8. Carlson GW, Page AJ, Cohen C, et al: Regional recurrence after negative sentinel lymph node biopsy for melanoma. Ann Surg 248: 378-386, 2008 9. Leong SP, Accortt NA, Essner R, et al: Impact of sentinel node status and other risk factors on the clinical outcome of head and neck melanoma patients. Arch Otolaryngol Head Neck Surg 132:370-373, 2006 10. Gomez-Rivera F, Santillan A, McMurphey AB, et al: Sentinel node biopsy in patients with cutaneous melanoma of the head and neck: recurrence and survival study. Head Neck 30:1284-1294, 2008 11. Erman AB, Collar RM, Griffith KA, et al: Sentinel lymph node biopsy is accurate and prognostic in head and neck melanoma. Cancer 118: 1040-1047, 2011 12. Neves RI, Reynolds BQ, Hazard SW, et al: Increased post-operative complications with methylene Blue versus lymphazurin in
13.
14.
15.
16.
17.
sentinel lymph node biopsies for skin cancers. J Surg Oncol 103:421-425, 2011 Carlson GW, Murray DR, Lyles RH, et al: Sentinel lymph node biopsy in the management of cutaneous head and neck melanoma. Plast Reconstr Surg 115:3, 2005 Carlson GW, Murray DR, Greenlee R, et al: Management of malignant melanoma of the head and neck using dynamic lymphoscintigraphy and gamma probe-guided sentinel lymph node biopsy. Arch Otolaryngol Head Neck Surg 126:433-437, 2000 McKean ME, Lee K, McGregor IA, McGregor IA: The distribution of lymph nodes in and around the parotid gland: an anatomical study. Br J Plast Surg 38:1-5, 1985 Fincher TR, O’Brien JC, McCarty TM, et al: Patterns of drainage and Recurrence following sentinel lymph node biopsy for cutaneous melanoma of the head and neck. Arch Otolaryngol Head Neck Surg 130:844-848, 2004 Loree TR, Tomljanovich PI, Cheney RT, et al: Intraparotid sentinel lymph node biopsy for head and neck melanoma. Laryngoscope 116: 1461-1464, 2006
Selective sentinel lymph node dissection in head and neck cutaneous melanoma Rogerio Izar Neves, MD, PhD, FACS From the Division of Plastic Surgery, Department of Surgery, Penn State Hershey Melanoma Center, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, Hershey, Pennsylvania. KEYWORDS Melanoma; Skin cancer; Sentinel lymph node; Surgery; Head and neck surgery
Sentinel lymph node biopsy accuracy and prognostic value in the head and neck region has been established. The article describes the current indications for the procedure, lymph node localization using lymphoscintigraphy and intra-operative blue dye injection, the surgical technique, and important recommendations to avoid complications in this very important anatomic region. © 2013 Elsevier Inc. All rights reserved.
Evolution of elective node dissections to sentinel lymph node biopsy; lymphoscintigraphy and technique O’Brien et al1 described the anatomically predicted drainage pattern of the head and neck in the hope that this would help guide more appropriate lymphadenectomies for head and neck cancers. Through clinical observation and the implementation of lymphoscintigraphy, the complexities of head and neck lymphatic drainage are better recognized, thus proving such models as O’Brien’s unreliable. Historically, occult metastases of head and neck melanomas were identified through elective node dissections. Factors such as tumor thickness, mitotic rate, ulceration, and anatomic location are known to be prognostic indicators, particularly with tumor staging.2 First described by Morton et al in 1992, sentinel lymph node biopsy (SLNB) has become a common staging procedure for cutaneous melanoma.3,4 Accurately predicting the status of the regional lymph node basin, a positive SLNB identifies a subset of patients who may benefit from com-
Address reprint requests and correspondence: Rogerio Izar Neves, MD, PhD, FACS, Division of Plastic Surgery, Department of Surgery, Penn State Hershey Melanoma Center, Pennsylvania State University, College of Medicine, Milton S. Hershey Medical Center, 500 University Drive, H071 PO. Box 850, Hershey, PA 17033-0850. E-mail address: [email protected]. 1043-1810/$ -see front matter © 2013 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.otot.2012.12.005
pletion lymphadenectomy and are candidates for adjuvant therapy and/or clinical trials. Proximity of cranial nerves and ambiguous lymphatic drainage pose unique challenges to performing the SLNB procedure in the head and neck region.1,5,6 Two large series (n ⫽ 3897) have demonstrated higher recurrence rates in previously mapped negative nodal basins in the head and neck region relative to other anatomic regions, suggesting inferior SLNB accuracy.7,8 For long time, consistent correlation between SLNB status and overall survival was lacking in head and neck melanoma series.9-11 Despite the general adoption of SLNB for extremity and truncal cutaneous melanoma, debate around SLNB accuracy and prognostic value in the head and neck region remained until Erman et al11 published one of the largest single-institution series of head and neck melanoma patients demonstrating that SLNB accuracy and prognostic value in the head and neck region are indeed comparable with other sites. Preoperative lymphoscintigraphy is required to define the regional lymph basin(s) that drain the primary site; to localize the predominant drainage channels leading to the basin(s); and to localize the number of sentinel lymph nodes (SLNs) within the basin(s) draining through separate lymphatic channels. The radiocolloid to be used will not be specified, as many agents are in common use. The radiocolloid in common use at our center is the sulfur-colloid injected intradermally on 4 sides of the primary or previous site of the primary tumor. The SLNs are marked externally on the skin of the subject. Dynamic lymphoscintigraphy is
14
Operative Techniques in Otolaryngology, Vol 24, No 1, March 2013
performed within 1 day of the wide excision and selective lymph node dissection, with initial images at 30-45 minutes and delayed images at 1-2 hours. If 2 or more regional lymph node basins are identified by lymphoscintigraphy, intraoperative lymphatic mapping and selective lymph node dissection will be performed on both lymph node groups, as it has not been possible to predict which nodal group would be the site of metastases.
Lymphatic mapping and selective sentinel lymphadenectomy The current indication for lymphatic mapping and SLNB at the Penn State Hershey Melanoma Center are as follows: ●
● ● ● ●
Recommended for primary melanomas with Breslow ⬎1 mm; offered for primary melanomas with Breslow 0.76-1 mm Clark ⱖIV without clinically detected lymph node metastasis Mitotic rate ⱖ1 Presence of ulceration We discuss and may offer the procedure for selected patients with primary melanomas with Breslow ⬍0.76 mm if young (ⱕ45 years), with ulceration or mitotic rate ⬎1; or in those patients with extensive regression (ⱖ75%)
Patients undergo preoperative lymphoscintigraphy to identify the regional lymph basin at risk for metastases, and the radioactive individual lymph nodes should have the site of the SLN identified by markings on the skin. At the time of the surgical procedure, the patient should be positioned for easy access to the regional lymph node basin. They are usually positioned supine for melanomas on the head and neck. Patients with primary melanomas arising on the upper extremities or back should be positioned in the lateral decubitus for access to the axillary or posterior cervical lymph basins. Lymphatic mapping with the blue dye is performed before wide local excision. In the head and neck region, 0.5-1.0 mL of isosulfan blue is injected intradermally with a 30-gauge needle around the site of the primary lesion or incision biopsy. After massage of the area for approximately 5 minutes, incision should be performed. In case a delay occurs beyond 30-45 minutes for any reason, reinjection should be performed due to a dye “washout”12 (Figure 1). An incision is made in the regional lymph basin of the expected lymphatic drainage, over the site of the SLN marked by preoperative lymphoscintigraphy and the operating gamma probe “hot” spot, and the incision is oriented for inclusion within a complete lymphadenectomy incision (Figure 2). Incision of approximately 3 cm may be adequate in most cases—larger incisions should be used without reservation if improved exposure will diminish the risk of complication such as nerve injury (Figure 3).
Figure 1 In the head and neck region, 0.5-1.0 mL of isosulfan blue is injected intradermally with a 30-gauge needle around the site of the primary lesion or incision biopsy. After approximately 5-10 minutes, incision should be performed. (Color version of figure is available online.)
Once the incision over the SLN has been made, usually an afferent blue lymphatic channel is found, which leads to the blue-stained node(s) (Figure 4). Careful exploration of the surrounding tissue is necessary to identify any additional nodes and to distinguish them from the SLN(s). Special care needs to be taken in the selective dissection of SLNs in the parotid or spinal accessory nerve area. A nerve stimulator is helpful to guide the dissection to avoid nerve injury. Dissect the lymph node from the surrounding tissue bed. Dissection is facilitated by grasping the tissue adjacent the node (not the node itself), to not crush or tear the lymph node (Figure 5). The probe is used to help identify the SLN. Nodes are labeled as “hot” in vivo if they are 3-fold or ex vivo if they are 6-fold more radioactive than background counts around the basin. Radioactive counts of the lymph node basin are taken once the nodes are removed to determine if any additional radioactive nodes are present (Figure 6).
Neves
Selective Sentinel Lymph Node Dissection
If so, these are excised even if not blue and are labeled as SLNs that are “hot, not blue,” if not colored by the dye mixture. The hot node-to-background ratio will vary depending on the particular radiocolloid used by the institution, as well as the number of hot nodes. Other radioactive nodes do not need to be removed if early lymphoscintigraphic images indicate these are not sentinel nodes but second echelon nodes because they are not directly connected to the primary site by a lymphatic channel. In this case, they are likely to be second echelon nodes or those even further down the drainage pathway. The single-photon emission computed tomography with computed tomography is helpful and should be used when available. After removal of the lymph node, take and record 2 more counts. Once the wound bed reading drops below 10% of ex-vivo reading, you have successfully removed the SLNs (Figure 7). Intraoperative frozen sections for SLNs are not recommended. However, the specimen should be sent immediately to pathology. Once it has been determined that the basin contains no additional “hot” or “blue” nodes, the deep
15
Figure 3 Incision of approximately 3 cm may be adequate in some cases—larger incisions should be used without reservation if improved exposure will diminish the risk of complication such as nerve injury. (Color version of figure is available online.)
and superficial fasciae are approximated in separate layers as per surgeon preference, and the subcutaneous tissue and skin are closed with absorbable suture. After changing gloves and instruments, the primary site is then widely excised. However, in head and neck melanomas, it is common to have the primary site close to the SLN, creating a strong “radioactive background” not allowing for an accurate SLN identification. In those cases, we perform the wide local excision first. The success of SLN biopsy depends on appropriate patient selection. Patients with palpable regional disease or distant metastasis are not candidates because additional prognostic information will not be gained.6,11 Additionally, patients who have had previous neck dissections or resection of the primary site with wide margins are not deemed candidates owing to lack of accuracy.
Figure 2 An incision is made in the regional lymph basin of the expected lymphatic drainage, over the site of the sentinel lymph node (SLN) marked by preoperative lymphoscintigraphy and the operating gamma probe “hot” spot, and the incision is oriented for inclusion within a complete lymphadenectomy incision. (Color version of figure is available online.)
Figure 4 Afferent blue lymphatic channel is found, which leads to the blue-stained node. (Color version of figure is available online.)
16
Operative Techniques in Otolaryngology, Vol 24, No 1, March 2013 tium, which can result in high background counts. This not only makes probe-guided localization difficult, but it also can mask the presence of positive SLNs in the parotid.13,14 Lower doses of radioactive tracer may be used to partially overcome this.
Intraparotid SLN mapping Primary tumors located on the ear, the cheek, the forehead, and anterior scalp commonly have lymphatic drainage through the parotid gland. SLNB of intraparotid nodes has been a topic of some controversy owing to the potential morbidity encountered with damage to the facial nerve. Sentinel nodes in the parotid gland tend to be small (3-6 mm), are densely adherent to surrounding fibrofatty tissue, and are difficult to discretely localize by gamma probe.13,15,16 When available, the use of intra-operative nerve monitoring is recommended. However, Ollila and colleagues studied the accuracy, sensitivity, and morbidity of intraparotid SLN biopsies. Patients who were found to have metastases in the intraparotid SLNs then underwent a facial nerve sparing parotidectomy and modified radical neck dissection, and only 2.6% of the patients experienced temporary facial nerve palsy, which completely resolved. Likewise, Loree and colleagues demonstrated no facial nerve complications.14,17
Neck anatomy and neck dissection In performing any procedure on the head and neck, it is of the utmost importance to know the anatomy and where Figure 5 Careful exploration of the surrounding tissue is necessary to identify any additional nodes and to distinguish them from the SLN(s). Special care needs to be taken in the selective dissection of SLNs in the parotid or spinal accessory nerve area. A nerve stimulator is helpful to guide the dissection to avoid nerve injury. Dissect the lymph node from the surrounding tissue bed. Dissection is facilitated by grasping the tissue adjacent the node (not the node itself), to not crush or tear the lymph node. (Color version of figure is available online.)
Locating the SLNs intraoperatively requires aiming the gamma probe at the areas previously marked by lymphoscintigraphy and obtaining the maximum count on the gamma probe. After removal of hot and/or blue nodes, the tissue is then reassessed with the gamma probe. When the background is ⬍10% of the maximum probe counts, no nodes containing technetium are considered present. On removal of the SLNs, care must be taken to ensure the specimen is not damaged. Metastatic foci may be present at any location within the node. Inadvertent cutting through the capsule or excessive use of cautery can interfere with histologic evaluation of the SLN and small metastases can be missed. Another common problem encountered is with the parotid gland. The parotid gland takes up free techne-
Figure 6 Radioactive counts of the lymph node basin are taken once the nodes are removed to determine if any additional radioactive nodes are present.
Neves
Selective Sentinel Lymph Node Dissection
17 face, and ear, or demonstrate drainage to this site by lymphoscintigraphy. Pathologic examination of the SLN must be performed by assessment of permanent sections prepared from formalin-fixed and paraffin-embedded tissues. Lymph nodes should not undergo frozen section examinations. In many SLNs, the number of tumor cells is small and such cells may be present only in the immediate peri-meridional tissue, and the necessary preparative steps may entirely remove the diagnostic tissue, leading to a false-negative interpretation. This hazard is compounded by the fact that after frozen section analysis, the residual frozen tissue is thawed and placed in formalin fixative at room temperature, which may lead to further tissue distortion. When the fixed tissue is sectioned, it may be necessary again to cut away considerable potentially diagnostic tissue to achieve the desirable full-face sections that will include the critical subcapsular sinus. Frozen sections are always more difficult to interpret, and rapid immunohistochemistry on frozen tissue is usually less readily interpretable. When the node specimen is sent to pathology, the requisition form should state the number of nodes, the anatomic locations, the color as observed in the operating room, and the radioactivity for each node recorded. The pathology report should confirm the number of nodes submitted in the specimen to be sure adequate tissue had been taken. We recommend that SLNs be evaluated at multiple levels, using conventional hematoxylin and eosin staining and immunohistochemistry with antibodies to several melanoma marker epitopes. The lymph node should be cut in 2 halves through its longest meridian. The 2 halves are then placed cut-face down in cassettes and fixed for not less than 24 hours. Once a full-face section is obtained, 12 serial sections are removed, and sections 1, 3, 5, and 10 are stained with hematoxylin and eosin (H&E). Section 2 is stained for S-100 protein, section 4 is stained for HMB-45, and section 6 is stained for MART-1 (Melan-A). Sections 7, 8, and 9 are negative controls for the immunoperoxidase studies, and sections 10, 11, and 12 are used to repeat any study that is technically unsatisfactory or for additional immunohistochemistry. Our own experience is that this technique balances desirably extensive sampling with cost-effectiveness.
Figure 7 The probe is used to help identify the SLN. Nodes are labeled as “hot” in vivo if they are 3-fold or ex vivo if they are 6-fold more radioactive than background counts around the basin. After removal of the lymph node, take and record 2 more counts. Once the wound bed reading drops below 10% of ex-vivo reading, you have successfully removed the SLNs. (Color version of figure is available online.)
particular structures lie to decrease the chance of morbidity. The anatomy for a neck dissection will be described in another chapter in this volume. If a micrometastasis is found in the SLN, the patient should receive a completion lymph node dissection. A superficial parotidectomy is required to remove the parotid nodes for primaries that arise on the anterior scalp,
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6. Morton DL, Cochran AJ, Thompson JF, et al: Sentinel node biopsy for early-stage melanoma: accuracy and morbidity in MSLT-I, an international multicenter trial. Ann Surg 242:302-311, 2005 7. Chao C, Wong SL, Edwards MJ, et al: Sentinel lymph node biopsy for head and neck melanomas. Ann Surg Oncol 10:21-26, 2003 8. Carlson GW, Page AJ, Cohen C, et al: Regional recurrence after negative sentinel lymph node biopsy for melanoma. Ann Surg 248: 378-386, 2008 9. Leong SP, Accortt NA, Essner R, et al: Impact of sentinel node status and other risk factors on the clinical outcome of head and neck melanoma patients. Arch Otolaryngol Head Neck Surg 132:370-373, 2006 10. Gomez-Rivera F, Santillan A, McMurphey AB, et al: Sentinel node biopsy in patients with cutaneous melanoma of the head and neck: recurrence and survival study. Head Neck 30:1284-1294, 2008 11. Erman AB, Collar RM, Griffith KA, et al: Sentinel lymph node biopsy is accurate and prognostic in head and neck melanoma. Cancer 118: 1040-1047, 2011 12. Neves RI, Reynolds BQ, Hazard SW, et al: Increased post-operative complications with methylene Blue versus lymphazurin in
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