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Giant cell tumor of the tendon sheath treated by brachytherapy (surface mold) technique—A technical illustration
Brachytherapy 8 (2009) 79e83
Giant cell tumor of the tendon sheath treated by brachytherapy (surface mold) techniquedA technical illustration Jayant Sastri Goda*, Pramod Patil, Chokkalingam Krishnappan, Dooraisamy Elangovan Department of Radiation Oncology and Medical Physics, Kailash Cancer Hospital, Vadodara, Gujarat, India
ABSTRACT
BACKGROUND: Giant cell tumors of the tendon sheath (GCTTS) are rare tumors involving diverse locations and have a tendency to recur postoperatively. Hence, radiotherapy (RT) plays a pivotal role as an adjuvant modality to prevent local recurrences. Although RT is an attractive treatment modality, treating these tumors in complex anatomical locations, such as the thumb with external beam radiation (EBRT), and ensuring adequate dosimetric coverage can be challenging. Literature regarding the optimal RT technique to treat GCTTS is limited in view of the rarity of these lesions and their complex anatomical locations. In this report, we describe a case of GCTTS of the thumb treated successfully with surface mold radiotherapy using a customized thermoplastic mold for the thumb. The patient tolerated the treatment well with excellent local control and functional outcome. METHODS AND MATERIALS: We developed a brachytherapy mold technique using a customized thermoplastic thumb mold with interstitial catheters and irradiated the target volume homogeneously using microselectron iridium-192 high-dose-rate (Nucletron B.V., Veenandaal, The Netherlands) sources. CONCLUSION: The index patient treated with surface mold therapy illustrates that this technique is safe and practical method to achieve excellent local tumor control with good functional outcome. Ó 2009 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
Keywords:
Giant cell tumor; Brachytherapy; IBU; Surface mold
Introduction Fibrohistiocytic proliferation of the synovial membrane encompasses a group of benign lesions that originate from the synovial membrane of the joint, bursae, and tendon sheath which are considered as a single anatomical unit (1,2). The localized extra-articular form of fibrohistiocytic proliferating lesion also known as giant cell tumor of tendon sheath (GCTTS) is more common than the diffuse intra-articular form, pigmented villonodular synovitis (PVNS) which is more aggressive and infrequent (3). These tumors are considered benign with a capacity for local recurrence as they have a tendency to spread to the neighboring synovium rendering complete excision often difficult (4). Definitive surgery with wide excision margins is the treatment of choice for GCTTS. Nevertheless, a good proportion of cases recur despite Received 16 May 2008; received in revised form 23 July 2008; accepted 24 July 2008. * Corresponding author. Department of Radiation Oncology and Medical Physics, Kailash Cancer Hospital, Muni Seva Ashram, Goraj, Vadodara, Gujarat, India 391760. E-mail address: [email protected] (J.S. Goda).
definitive resection (5). Fortunately, these recurrences are usually nondestructive and are adequately controlled by surgical re-excision and radiation therapy. However, in anatomical locations such as the thumb, radiation treatment with conventional photon beams will result in excessive exit dose to the nail bed while treating with electrons will result in an inhomogenous dose distribution potentially underdosing the target volume. Therefore, surface mold radiotherapy (moulage) using brachytherapy sources is an attractive alternative technique for treating tumors located at such sites. In this report, we present a case of GCTTS of the thumb irradiated in a unique way by using brachytherapy moulage technique with microselectron iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy (Nucletron B.V., Veenandaal, The Netherlands) Although labor intensive, we were able to achieve excellent dosimetric and clinical results with this technique.
Case history A 54-year-old female presented with well-defined slowgrowing circumferential, painless, and recurrent nodule
1538-4721/09/$ e see front matter Ó 2009 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.brachy.2008.07.008
80
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
over the palmar aspect of the right thumb. This lump gradually increased in size and ulcerated with breakdown of the skin surface (Fig. 1). Eventually she underwent wide excision of the nodule. Histopathology of the nodule revealed proliferation of fibroblast and histiocytes with collagen in between the cells interspersed with scattered giant cells. Based on the morphologic findings on histopathology, a diagnosis of giant cell tumor of tendon sheath was reported. After excision of tumor, the patient was considered for radiation therapy in view of high risk of recurrence after surgery. Radiation therapy was delivered via surface mold to a dose of 30 Gy in 10 fractions using HDR 192Ir source. The patient tolerated the treatment quite well and one month postradiation therapy, she developed a grade-II radiationeinduced skin reactions, which resolved over a couple of weeks with conservative management(Fig. 2). Twentyone months after radiotherapy, at last followup visit, there was no evidence of local recurrence of disease, although there was evidence of mild fibrosis over the thumb (Fig. 3) The patient retained most of her thumb functions although there was evidence of reduced power in her pincer grasp and has been referred for active physiotherapy. Methods and materials Immobilization of thumb and construction of customized thermoplastic mold A customized thermoplastic thumb mold was made with the help of orfit (POCL, Mumbai, India) such that the thumb could easily slide through it. A 5-mm thick paraffin wax bolus was wrapped around the mask. The basic rationale was to avoid delivering high dose to the skin at the time of treatment. Six applicator needles each of 8-cm length were placed at a uniform spacing of 1 cm each on the thermoplastic mold with help of graph sheet (Fig. 4). These applicators were tagged for the purpose of identification at the time of planning and treatment as shown in Fig. 4. The entire set of applicators covered at least half
Fig. 1. Ulceroproliferative lesion on the palmar aspect of the thumb.
Fig. 2. One month postradiotherapy showing acute Grade-II skin reactions on the thumb.
the circumference of the thumb ensuring adequate dosimetric coverage of the target volume. Furthermore, we ensured that sufficient distance was maintained from the nail so as to avoid radiating the nail bed. Planning Once immobilization was achieved, dummy sources were inserted into the applicator needles mounted on the thermoplastic mold. Orthogonal radiographs of the thumb with the dummy sources were taken by fixing the C-arm at 270 and rotating the L-arm of the fluoroscope attached to the integrated brachytherapy unit (IBU) (Nucletron B.V.). Additional radiographs were taken at oblique angles for the purpose of identification of all the needles on the radiographs (Fig. 5). The acquired images were then exported to three-dimensional (3-D) treatment planning system (3-D Plato TPS, Nucletron B.V.) After transferring the images to the planning system, the applicators were identified and reconstructed from the oblique radiographs in the TPS. The indexer length was determined with the help of source position simulator. For dosimetric planning, the source dwell position was kept at 2.5 mm and at a step size of two for the required treatment length. The required treatment length was determined from the preoperative axial CT scan
Fig. 3. Twenty-one months postradiotherapy showing subcutaneous fibrosis in the irradiated region of the thumb.
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
Fig. 4. Photograph showing the thermoplastic mold with the mounted applicator needles equispaced at 1 cm.
images and counter checked on the IBU fluoroscopic images. Based on the CT images, our treatment length was 4 cm and the target volume was 15 cm3 so as to ensure adequate coverage of the postoperative tumor bed. The basaldose-rate (BDR) points were kept 1 cm equidistant to all active source positions based on the Paris system. Dose point optimization was performed and dose volume histograms (DVH) were generated to check the dose distribution
81
to the target volume, underlying bone and the nail bed. The final plan achieved excellent coverage of the target volume and with coverage of the entire target by the prescribed dose as shown by the 100% isodose surface in red (Fig. 6). A CTebased 3-D plan was generated and compared with IBUebased orthogonal radiograph plans. We observed a variation of only 1.5% between the two plans. Hence, we continued with the IBUebased plan for all treatment fractions. Dose volume histograms (DVH) were generated from CTebased plan for the normal tissues (nail bed and bone) and the target volume. Maximum dose to the nail bed was 97% of the prescribed dose (30% volume of nail bed received 66% of prescribed dose, whereas 70% volume of nail bed received 52% of prescribed dose). Maximum dose to the bone was 120% of prescribed dose. Only 1% volume of bone received more than the prescribed dose.
Treatment The patient was treated with a radiation dose of 30 Gy in 10 fractions over 5 days (radiation dose per fraction was 3 Gy given twice daily, 6e8 h apart) using 192Ir HDR microselectron (Fig. 7). For quality assurance purpose, the geometric accuracy of the applicators was confirmed with
Fig. 5. Photograph of orthogonal and oblique X-rays showing the applicator needles and dummy sources.
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J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
Fig. 6. A and B: Dosimetry photographs showing the axial, sagittal, and coronal planes of the radioactive sources with surrounding isodose curves. The red colored line that covers the intended treatment length defines the 100% isodose curve (for interpretation of the reference to color in this figure legend, the reader is referred to the web version of this article).
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
83
Although the surface mold technique is a potentially attractive method for treating such tumors at these locations, we would like to draw attention to some of the potential drawbacks of this technique. As for all brachytherapy techniques, this technique is labor intensive and time consuming. Moreover, one of the critical elements is to ensure the geometrical accuracy and reproducibility of the applicator position as the treatment volume is small and any variation in the position of the applicators may lead to inhomogenous dose distribution thereby undertreating the target volume. Fig. 7. Patient’s thumb treated with surface mold connected to the HDR machine using source transfer tubes.
the help of online verification feature in IBU before every fraction.
Discussion Despite their nonmalignant behavior, giant cell tumors of the tendon sheath (GCTTS) tend to have a high rate of recurrence after resection. Literature studies have shown recurrence rates of 9e44% (5, 6). In view of high recurrence rates, radiation therapy is considered to be an important adjunct treatment modality in the postsurgical management of GCTTS. Radiation therapy is quite effective in preventing local recurrences thereby improving long-term control rates in these tumors (5, 6). Contemporary techniques have used conventional external beam radiotherapy with photons or electrons to treat these tumors with excellent results (5e7). However, treating these tumors in complex locations, such as the thumb could result in overtreating the adjoining normal tissues when photons are used or result in an inhomogenous dose distribution leading to undertreatment of the target volume when electrons are used. An alternative treatment method is to use a brachytherapy moulage technique (surface mold) which not only gives a homogenous dose distribution to the target volume but at the same time spares the adjacent normal tissues because of the special physical properties of 192Ir radioactive sources (Fig. 6).
Conclusion The technique of treating the thumb with surface mold is a good substitute to external beam radiation. This technique is labor intensive requiring additional preparation time and planning compared with the standard EBRT techniques. Nevertheless, our efforts in this case seemed worthwhile and logical as we achieved a homogenous dose distribution to the target volume. We believe that this technique illustrates an achievable and reproducible method of irradiating such rare tumors situated in complex locations.
References [1] Weiss SW, Goldblum JR. Tumours of synovial tissue. In: Enzinger FM, Weiss SW, editors. Soft tissue tumours. 4th ed. St Louis: CV Mosby; 2001. p. 1037e1060. [2] Jaffe HL, Lichenstein L, Sutro CJ. Pigmented villonodular synovitis, bursitis and tenosynovitis. Arch Pathol Lab Med 1941;31:731e765. [3] Harris O, Ritchie DA, Maginnis R, et al. MRI of the giant cell tumour of tendon sheath and nodular synovitis of the foot and ankle. The foot 2002;13:19e29. [4] Schajowicz F. Tumors and tumor like lesions of bone and joints. New York: Springer-Verlag; 1981. [5] Kotwal PP, Gupta V, Malhotra R. Giant-cell tumour of the tendon sheath. Is radiotherapy indicated to prevent recurrence after surgery? J Bone Joint Surg Br 2000;82:571e573. [6] O’ Sullivan B, Cummings B, Catton C, et al. Outcome following radiation treatment for high-risk pigmented villonodular synovitis. Int J Radiat Oncol Biol Phys 1995;32:777e786. [7] Jaffe HL. In tumours and tumourous conditions of the bones and joints. London: Henry Kimpton; 1958.
Giant cell tumor of the tendon sheath treated by brachytherapy (surface mold) techniquedA technical illustration Jayant Sastri Goda*, Pramod Patil, Chokkalingam Krishnappan, Dooraisamy Elangovan Department of Radiation Oncology and Medical Physics, Kailash Cancer Hospital, Vadodara, Gujarat, India
ABSTRACT
BACKGROUND: Giant cell tumors of the tendon sheath (GCTTS) are rare tumors involving diverse locations and have a tendency to recur postoperatively. Hence, radiotherapy (RT) plays a pivotal role as an adjuvant modality to prevent local recurrences. Although RT is an attractive treatment modality, treating these tumors in complex anatomical locations, such as the thumb with external beam radiation (EBRT), and ensuring adequate dosimetric coverage can be challenging. Literature regarding the optimal RT technique to treat GCTTS is limited in view of the rarity of these lesions and their complex anatomical locations. In this report, we describe a case of GCTTS of the thumb treated successfully with surface mold radiotherapy using a customized thermoplastic mold for the thumb. The patient tolerated the treatment well with excellent local control and functional outcome. METHODS AND MATERIALS: We developed a brachytherapy mold technique using a customized thermoplastic thumb mold with interstitial catheters and irradiated the target volume homogeneously using microselectron iridium-192 high-dose-rate (Nucletron B.V., Veenandaal, The Netherlands) sources. CONCLUSION: The index patient treated with surface mold therapy illustrates that this technique is safe and practical method to achieve excellent local tumor control with good functional outcome. Ó 2009 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
Keywords:
Giant cell tumor; Brachytherapy; IBU; Surface mold
Introduction Fibrohistiocytic proliferation of the synovial membrane encompasses a group of benign lesions that originate from the synovial membrane of the joint, bursae, and tendon sheath which are considered as a single anatomical unit (1,2). The localized extra-articular form of fibrohistiocytic proliferating lesion also known as giant cell tumor of tendon sheath (GCTTS) is more common than the diffuse intra-articular form, pigmented villonodular synovitis (PVNS) which is more aggressive and infrequent (3). These tumors are considered benign with a capacity for local recurrence as they have a tendency to spread to the neighboring synovium rendering complete excision often difficult (4). Definitive surgery with wide excision margins is the treatment of choice for GCTTS. Nevertheless, a good proportion of cases recur despite Received 16 May 2008; received in revised form 23 July 2008; accepted 24 July 2008. * Corresponding author. Department of Radiation Oncology and Medical Physics, Kailash Cancer Hospital, Muni Seva Ashram, Goraj, Vadodara, Gujarat, India 391760. E-mail address: [email protected] (J.S. Goda).
definitive resection (5). Fortunately, these recurrences are usually nondestructive and are adequately controlled by surgical re-excision and radiation therapy. However, in anatomical locations such as the thumb, radiation treatment with conventional photon beams will result in excessive exit dose to the nail bed while treating with electrons will result in an inhomogenous dose distribution potentially underdosing the target volume. Therefore, surface mold radiotherapy (moulage) using brachytherapy sources is an attractive alternative technique for treating tumors located at such sites. In this report, we present a case of GCTTS of the thumb irradiated in a unique way by using brachytherapy moulage technique with microselectron iridium-192 (192Ir) high-dose-rate (HDR) brachytherapy (Nucletron B.V., Veenandaal, The Netherlands) Although labor intensive, we were able to achieve excellent dosimetric and clinical results with this technique.
Case history A 54-year-old female presented with well-defined slowgrowing circumferential, painless, and recurrent nodule
1538-4721/09/$ e see front matter Ó 2009 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.brachy.2008.07.008
80
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
over the palmar aspect of the right thumb. This lump gradually increased in size and ulcerated with breakdown of the skin surface (Fig. 1). Eventually she underwent wide excision of the nodule. Histopathology of the nodule revealed proliferation of fibroblast and histiocytes with collagen in between the cells interspersed with scattered giant cells. Based on the morphologic findings on histopathology, a diagnosis of giant cell tumor of tendon sheath was reported. After excision of tumor, the patient was considered for radiation therapy in view of high risk of recurrence after surgery. Radiation therapy was delivered via surface mold to a dose of 30 Gy in 10 fractions using HDR 192Ir source. The patient tolerated the treatment quite well and one month postradiation therapy, she developed a grade-II radiationeinduced skin reactions, which resolved over a couple of weeks with conservative management(Fig. 2). Twentyone months after radiotherapy, at last followup visit, there was no evidence of local recurrence of disease, although there was evidence of mild fibrosis over the thumb (Fig. 3) The patient retained most of her thumb functions although there was evidence of reduced power in her pincer grasp and has been referred for active physiotherapy. Methods and materials Immobilization of thumb and construction of customized thermoplastic mold A customized thermoplastic thumb mold was made with the help of orfit (POCL, Mumbai, India) such that the thumb could easily slide through it. A 5-mm thick paraffin wax bolus was wrapped around the mask. The basic rationale was to avoid delivering high dose to the skin at the time of treatment. Six applicator needles each of 8-cm length were placed at a uniform spacing of 1 cm each on the thermoplastic mold with help of graph sheet (Fig. 4). These applicators were tagged for the purpose of identification at the time of planning and treatment as shown in Fig. 4. The entire set of applicators covered at least half
Fig. 1. Ulceroproliferative lesion on the palmar aspect of the thumb.
Fig. 2. One month postradiotherapy showing acute Grade-II skin reactions on the thumb.
the circumference of the thumb ensuring adequate dosimetric coverage of the target volume. Furthermore, we ensured that sufficient distance was maintained from the nail so as to avoid radiating the nail bed. Planning Once immobilization was achieved, dummy sources were inserted into the applicator needles mounted on the thermoplastic mold. Orthogonal radiographs of the thumb with the dummy sources were taken by fixing the C-arm at 270 and rotating the L-arm of the fluoroscope attached to the integrated brachytherapy unit (IBU) (Nucletron B.V.). Additional radiographs were taken at oblique angles for the purpose of identification of all the needles on the radiographs (Fig. 5). The acquired images were then exported to three-dimensional (3-D) treatment planning system (3-D Plato TPS, Nucletron B.V.) After transferring the images to the planning system, the applicators were identified and reconstructed from the oblique radiographs in the TPS. The indexer length was determined with the help of source position simulator. For dosimetric planning, the source dwell position was kept at 2.5 mm and at a step size of two for the required treatment length. The required treatment length was determined from the preoperative axial CT scan
Fig. 3. Twenty-one months postradiotherapy showing subcutaneous fibrosis in the irradiated region of the thumb.
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
Fig. 4. Photograph showing the thermoplastic mold with the mounted applicator needles equispaced at 1 cm.
images and counter checked on the IBU fluoroscopic images. Based on the CT images, our treatment length was 4 cm and the target volume was 15 cm3 so as to ensure adequate coverage of the postoperative tumor bed. The basaldose-rate (BDR) points were kept 1 cm equidistant to all active source positions based on the Paris system. Dose point optimization was performed and dose volume histograms (DVH) were generated to check the dose distribution
81
to the target volume, underlying bone and the nail bed. The final plan achieved excellent coverage of the target volume and with coverage of the entire target by the prescribed dose as shown by the 100% isodose surface in red (Fig. 6). A CTebased 3-D plan was generated and compared with IBUebased orthogonal radiograph plans. We observed a variation of only 1.5% between the two plans. Hence, we continued with the IBUebased plan for all treatment fractions. Dose volume histograms (DVH) were generated from CTebased plan for the normal tissues (nail bed and bone) and the target volume. Maximum dose to the nail bed was 97% of the prescribed dose (30% volume of nail bed received 66% of prescribed dose, whereas 70% volume of nail bed received 52% of prescribed dose). Maximum dose to the bone was 120% of prescribed dose. Only 1% volume of bone received more than the prescribed dose.
Treatment The patient was treated with a radiation dose of 30 Gy in 10 fractions over 5 days (radiation dose per fraction was 3 Gy given twice daily, 6e8 h apart) using 192Ir HDR microselectron (Fig. 7). For quality assurance purpose, the geometric accuracy of the applicators was confirmed with
Fig. 5. Photograph of orthogonal and oblique X-rays showing the applicator needles and dummy sources.
82
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
Fig. 6. A and B: Dosimetry photographs showing the axial, sagittal, and coronal planes of the radioactive sources with surrounding isodose curves. The red colored line that covers the intended treatment length defines the 100% isodose curve (for interpretation of the reference to color in this figure legend, the reader is referred to the web version of this article).
J.S. Goda et al. / Brachytherapy 8 (2009) 79e83
83
Although the surface mold technique is a potentially attractive method for treating such tumors at these locations, we would like to draw attention to some of the potential drawbacks of this technique. As for all brachytherapy techniques, this technique is labor intensive and time consuming. Moreover, one of the critical elements is to ensure the geometrical accuracy and reproducibility of the applicator position as the treatment volume is small and any variation in the position of the applicators may lead to inhomogenous dose distribution thereby undertreating the target volume. Fig. 7. Patient’s thumb treated with surface mold connected to the HDR machine using source transfer tubes.
the help of online verification feature in IBU before every fraction.
Discussion Despite their nonmalignant behavior, giant cell tumors of the tendon sheath (GCTTS) tend to have a high rate of recurrence after resection. Literature studies have shown recurrence rates of 9e44% (5, 6). In view of high recurrence rates, radiation therapy is considered to be an important adjunct treatment modality in the postsurgical management of GCTTS. Radiation therapy is quite effective in preventing local recurrences thereby improving long-term control rates in these tumors (5, 6). Contemporary techniques have used conventional external beam radiotherapy with photons or electrons to treat these tumors with excellent results (5e7). However, treating these tumors in complex locations, such as the thumb could result in overtreating the adjoining normal tissues when photons are used or result in an inhomogenous dose distribution leading to undertreatment of the target volume when electrons are used. An alternative treatment method is to use a brachytherapy moulage technique (surface mold) which not only gives a homogenous dose distribution to the target volume but at the same time spares the adjacent normal tissues because of the special physical properties of 192Ir radioactive sources (Fig. 6).
Conclusion The technique of treating the thumb with surface mold is a good substitute to external beam radiation. This technique is labor intensive requiring additional preparation time and planning compared with the standard EBRT techniques. Nevertheless, our efforts in this case seemed worthwhile and logical as we achieved a homogenous dose distribution to the target volume. We believe that this technique illustrates an achievable and reproducible method of irradiating such rare tumors situated in complex locations.
References [1] Weiss SW, Goldblum JR. Tumours of synovial tissue. In: Enzinger FM, Weiss SW, editors. Soft tissue tumours. 4th ed. St Louis: CV Mosby; 2001. p. 1037e1060. [2] Jaffe HL, Lichenstein L, Sutro CJ. Pigmented villonodular synovitis, bursitis and tenosynovitis. Arch Pathol Lab Med 1941;31:731e765. [3] Harris O, Ritchie DA, Maginnis R, et al. MRI of the giant cell tumour of tendon sheath and nodular synovitis of the foot and ankle. The foot 2002;13:19e29. [4] Schajowicz F. Tumors and tumor like lesions of bone and joints. New York: Springer-Verlag; 1981. [5] Kotwal PP, Gupta V, Malhotra R. Giant-cell tumour of the tendon sheath. Is radiotherapy indicated to prevent recurrence after surgery? J Bone Joint Surg Br 2000;82:571e573. [6] O’ Sullivan B, Cummings B, Catton C, et al. Outcome following radiation treatment for high-risk pigmented villonodular synovitis. Int J Radiat Oncol Biol Phys 1995;32:777e786. [7] Jaffe HL. In tumours and tumourous conditions of the bones and joints. London: Henry Kimpton; 1958.