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Soft-Tissue Myoepithelioma of the Hypothenar Region: A Case Report
Soft-Tissue Myoepithelioma of the Hypothenar Region: A Case Report Mayia Pilavaki, MD, PhD, Panagiotis Givissis, MD, PhD, Valesia Tzarou, MD, Panagiotis Palladas, MD, John Pournaras, MD, PhD From the Department of Radiology, General Hospital G. Papanikolaou; A’Orthopaedic Department, Aristotelian University of Thessaloniki, General Hospital G. Papanikolaou; and Laboratory of Pathology, General Hospital G. Papanikolaou, Thessaloniki, Greece.
Myoepithelial tumors only recently have been recognized as occurring primarily in soft tissue, and only a few cases have been described in the literature. The occurrence of these tumors in the hand is even more limited. In this article, we review the clinical, radiologic, and histologic features of a benign myoepithelioma of the hypothenar region of the left hand. (J Hand Surg 2007;32A:674 – 676. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Hand, magnetic resonance imaging, myoepithelioma, soft tissue.
yoepithelial tumors of the soft tissue are rare, although they are relatively common in the skin and salivary glands, especially the parotid gland. In a clinicopathologic study of 101 myoepithelial tumors occurring in soft tissue, only 5 cases originated in the hand.1 To our knowledge, there has been only 1 case report2 of a soft-tissue myoepithelioma originating in the hand— one in which the tumor was located in the thenar eminence of the left hand. Unlike our case, in which the patient presented with enlargement of the hypothenar region only, that patient had dilated tortuous veins on the overlying skin, and the plain radiograph showed a soft-tissue enlargement containing a nodular calcification. Its characteristics on magnetic resonance image (MRI) generally resembled those of our case, the only differences being that in our case the tumor was lobulated and the signal intensity on T2-weighted images was heterogeneous.
M
Case Report A 50-year-old woman presented with a 4-year history of a slow-growing mass in the hypothenar region of the left hand (Fig. 1). Neither previous experience of trauma nor any relevant past medical or surgical history was noted. Physical examination showed a nontender, firm, 3 ⫻ 3-cm mass overlying the volar aspect of the hypothenar eminence of the left hand. The overlying skin was smooth, nonadherent, and 674
The Journal of Hand Surgery
without ulceration or dilated vessels. Physical examination of the axillary area showed no adenopathy. A plain radiograph showed a soft-tissue enlargement without calcifications or bone involvement. An MRI of the hand was obtained both with and without gadolinium. The examination showed an approximately 3 ⫻ 3 ⫻ 1-cm, well-circumscribed, lobulated mass in the subcutaneous tissue of the left hypothenar area. On T2-weighted images, the tumor had a heterogeneous, predominantly increased signal with internal septa of low-signal intensity (Fig. 2). Because of the slow-growing nature and benign radiographic appearance of the mass, an excisional biopsy was performed. Under an axillary block and tourniquet control, a zig-zag incision was made over the mass, which was found to be encapsulated, not adherent to the skin but partially adherent to the palmar aponeurosis (Fig. 3). The sensory branch of the ulnar nerve was identified and protected. A marginal excision of the tumor was performed. The postoperative period was uneventful. Histologically, the tumor had a lobulated architecture and was composed of epithelioid cells and myoepithelial elements in the chondromyxoid and fibrous stroma (Fig. 4). The epithelioid cells were in small groups and had an eosinophilic cytoplasm. Neither mitosis nor necrosis was found. Immunohistochemically, the tumor cells expressed cytokeratin, vimen-
Pilavaki et al / A Case of Myoepithelioma of the Hand
Figure 1. Preoperative photograph of the left hand.
tin, and S-100 protein. Cytokeratin staining was observed in epithelial cells, and vimentin staining was seen in the mesenchymal cells. S-100 protein staining was observed focally and was confined to myoepithelial cells. Coexpression of these antigens favored the histologic diagnosis of mixed tumor/ myoepithelioma of soft tissue. Follow-up examination performed 9 months later showed no local recurrence or metastasis.
Discussion Well-characterized in the salivary glands, myoepitheliomas and mixed tumors (pleomorphic adeno-
Figure 2. Sagittal T2-weighted MRI shows the tumor (arrow) to be primarily of high signal intensity with internal septa of low signal intensity (arrowheads).
675
Figure 3. Intraoperative photograph of the tumor being excised en bloc.
mas) were recognized only recently as occurring in soft tissue.1,3 Histologically, these tumors show the same morphologic spectrum observed in their salivary gland counterparts.4 Myoepitheliomas of soft tissue are often lobulated, and the most frequent architectural pattern is reticular with chondromyxoid or hyalinized stroma.1,3 They typically behave in a benign fashion with a low but unpredictable risk for local recurrence (approximately 20%). There are rare examples of myoepitheliomas of soft tissue that have developed metastases to the lung and regional lymph nodes.1,4,5 The histologic feature that is usually associated with recurrence or metastasis is the presence of moderate to severe cytologic atypia.1,3 Although malignant myoepitheliomas have been reported to occur primarily in soft tissue,6 no malignant degeneration of a primarily benign tumor has been reported. However, Harada et al6 report a case in which
Figure 4. Microscopic appearance shows epithelioid cells in chondromyxoid (asterisks) and fibrous stroma (arrows) (hematoxylin and eosin stain; magnification, ⫻25).
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The Journal of Hand Surgery / Vol. 32A No. 5 May–June 2007
malignant transformation of a pre-existing benign tumor is considered possible. Myoepitheliomas of soft tissue are equally common in male and female patients, occurring in a wide age range with a peak in the third to fifth decades, most commonly in the limbs and the limb girdles.1,4 The vast majority of cases arise in the subcutaneous or deep subfascial soft tissue. Most patients present with painless swelling ranging in duration from a few weeks to several years.4 The MRI appearance of soft-tissue myoepitheliomas has been limited because these tumors are rare, especially in the hand. In this case, the MRI features of the lesion included a subcutaneous, well-circumscribed, lobulated mass. On T1-weighted images, the signal intensity of the tumor was low with areas of high signal intensity corresponding to hemorrhagic areas. On T2-weighted images, the tumor had heterogeneous, predominantly increased signal with internal septa of low signal intensity. This morphologic appearance reflected the chondromyxoid and fibrous stroma. T1-weighted images after an intravenous gadolinium infusion showed nonhomogeneous enhancement. The enhancing areas of the tumor correlated with areas of tissue vascularity and increased cellular components, because the nonenhanced areas corresponded to the fibrous tissue. Differential diagnoses included subcutaneous tumors with the same or similar MRI appearance such as hemangioma, myxoma, and myxoid liposarcoma.7 The absence of calcifications or ossifications excluded the diagnosis of extraskeletal cartilaginous tumors. Myoepithelial tumors must be considered in the differential diagnosis of soft-tissue tumors of the hand. The rarity of this tumor in the soft tissue has not enabled considerable study of the possibility of malignant degeneration. The additional possibility of
local recurrence and metastasis suggest a complete excision of the tumor and appropriate follow-up examinations of the patient. A preoperative diagnosis based on the MRI characteristics of these tumors may prevent unnecessary biopsy. Received for publication October 30, 2006; accepted in revised form February 27, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Mayia Pilavaki, MD, PhD, Mitropolitou Genadiou 20A, 57010, Hortiatis, Thessaloniki, Greece; e-mail: [email protected]. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A05-0014$32.00/0 doi:10.1016/j.jhsa.2007.02.022
References 1. Hornick JL, Fletcher CD. Myoepithelial tumors of soft tissue: a clinicopathologic and immunohistochemical study of 101 cases evaluation of prognostic parameters. Am J Surg Pathol 2003;27:1183–1196. 2. Hamada K, Ueda T, Tomita Y, Yoshikawa H, Hatazawa J. Myoepithelioma of soft tissue originating from the hand: 18 F-FDG PET features. AJR Am J Roentgenol 2006;186: 270 –271. 3. Go JH. A case of soft tissue myoepithelial tumor arising in masticator space. Yonsei Med J 2005;46:710 –714. 4. Kilpatrick SE, Limon J. Mixed tumour/myoepithelioma/parachordoma. In: World Health Organization classification of tumours: pathology and genetics of tumours of soft tissue and bone. Lyon: IARC Press, 2002:198 –199. 5. Kilpatrick SE, Hitchcock MG, Kraus MD, Calonje E, Fletcher CD. Mixed tumors and myoepitheliomas of soft tissue: a clinicopathologic study of 19 cases with a unifying concept. Am J Surg Pathol 1997;21:13–22. 6. Harada O, Ota H, Nakayama J. Malignant myoepithelioma (myoepithelial carcinoma) of soft tissue. Pathol Int 2005;55: 510 –513. 7. Capelastegui A, Astigarraga E, Fernandez-Canton G, Saralegui I, Larena JA. Masses and pseudomasses of the hand and wrist: MR findings in 134 cases. Skeletal Radiol 1999;28: 498 –507.
Myoepithelial tumors only recently have been recognized as occurring primarily in soft tissue, and only a few cases have been described in the literature. The occurrence of these tumors in the hand is even more limited. In this article, we review the clinical, radiologic, and histologic features of a benign myoepithelioma of the hypothenar region of the left hand. (J Hand Surg 2007;32A:674 – 676. Copyright © 2007 by the American Society for Surgery of the Hand.) Key words: Hand, magnetic resonance imaging, myoepithelioma, soft tissue.
yoepithelial tumors of the soft tissue are rare, although they are relatively common in the skin and salivary glands, especially the parotid gland. In a clinicopathologic study of 101 myoepithelial tumors occurring in soft tissue, only 5 cases originated in the hand.1 To our knowledge, there has been only 1 case report2 of a soft-tissue myoepithelioma originating in the hand— one in which the tumor was located in the thenar eminence of the left hand. Unlike our case, in which the patient presented with enlargement of the hypothenar region only, that patient had dilated tortuous veins on the overlying skin, and the plain radiograph showed a soft-tissue enlargement containing a nodular calcification. Its characteristics on magnetic resonance image (MRI) generally resembled those of our case, the only differences being that in our case the tumor was lobulated and the signal intensity on T2-weighted images was heterogeneous.
M
Case Report A 50-year-old woman presented with a 4-year history of a slow-growing mass in the hypothenar region of the left hand (Fig. 1). Neither previous experience of trauma nor any relevant past medical or surgical history was noted. Physical examination showed a nontender, firm, 3 ⫻ 3-cm mass overlying the volar aspect of the hypothenar eminence of the left hand. The overlying skin was smooth, nonadherent, and 674
The Journal of Hand Surgery
without ulceration or dilated vessels. Physical examination of the axillary area showed no adenopathy. A plain radiograph showed a soft-tissue enlargement without calcifications or bone involvement. An MRI of the hand was obtained both with and without gadolinium. The examination showed an approximately 3 ⫻ 3 ⫻ 1-cm, well-circumscribed, lobulated mass in the subcutaneous tissue of the left hypothenar area. On T2-weighted images, the tumor had a heterogeneous, predominantly increased signal with internal septa of low-signal intensity (Fig. 2). Because of the slow-growing nature and benign radiographic appearance of the mass, an excisional biopsy was performed. Under an axillary block and tourniquet control, a zig-zag incision was made over the mass, which was found to be encapsulated, not adherent to the skin but partially adherent to the palmar aponeurosis (Fig. 3). The sensory branch of the ulnar nerve was identified and protected. A marginal excision of the tumor was performed. The postoperative period was uneventful. Histologically, the tumor had a lobulated architecture and was composed of epithelioid cells and myoepithelial elements in the chondromyxoid and fibrous stroma (Fig. 4). The epithelioid cells were in small groups and had an eosinophilic cytoplasm. Neither mitosis nor necrosis was found. Immunohistochemically, the tumor cells expressed cytokeratin, vimen-
Pilavaki et al / A Case of Myoepithelioma of the Hand
Figure 1. Preoperative photograph of the left hand.
tin, and S-100 protein. Cytokeratin staining was observed in epithelial cells, and vimentin staining was seen in the mesenchymal cells. S-100 protein staining was observed focally and was confined to myoepithelial cells. Coexpression of these antigens favored the histologic diagnosis of mixed tumor/ myoepithelioma of soft tissue. Follow-up examination performed 9 months later showed no local recurrence or metastasis.
Discussion Well-characterized in the salivary glands, myoepitheliomas and mixed tumors (pleomorphic adeno-
Figure 2. Sagittal T2-weighted MRI shows the tumor (arrow) to be primarily of high signal intensity with internal septa of low signal intensity (arrowheads).
675
Figure 3. Intraoperative photograph of the tumor being excised en bloc.
mas) were recognized only recently as occurring in soft tissue.1,3 Histologically, these tumors show the same morphologic spectrum observed in their salivary gland counterparts.4 Myoepitheliomas of soft tissue are often lobulated, and the most frequent architectural pattern is reticular with chondromyxoid or hyalinized stroma.1,3 They typically behave in a benign fashion with a low but unpredictable risk for local recurrence (approximately 20%). There are rare examples of myoepitheliomas of soft tissue that have developed metastases to the lung and regional lymph nodes.1,4,5 The histologic feature that is usually associated with recurrence or metastasis is the presence of moderate to severe cytologic atypia.1,3 Although malignant myoepitheliomas have been reported to occur primarily in soft tissue,6 no malignant degeneration of a primarily benign tumor has been reported. However, Harada et al6 report a case in which
Figure 4. Microscopic appearance shows epithelioid cells in chondromyxoid (asterisks) and fibrous stroma (arrows) (hematoxylin and eosin stain; magnification, ⫻25).
676
The Journal of Hand Surgery / Vol. 32A No. 5 May–June 2007
malignant transformation of a pre-existing benign tumor is considered possible. Myoepitheliomas of soft tissue are equally common in male and female patients, occurring in a wide age range with a peak in the third to fifth decades, most commonly in the limbs and the limb girdles.1,4 The vast majority of cases arise in the subcutaneous or deep subfascial soft tissue. Most patients present with painless swelling ranging in duration from a few weeks to several years.4 The MRI appearance of soft-tissue myoepitheliomas has been limited because these tumors are rare, especially in the hand. In this case, the MRI features of the lesion included a subcutaneous, well-circumscribed, lobulated mass. On T1-weighted images, the signal intensity of the tumor was low with areas of high signal intensity corresponding to hemorrhagic areas. On T2-weighted images, the tumor had heterogeneous, predominantly increased signal with internal septa of low signal intensity. This morphologic appearance reflected the chondromyxoid and fibrous stroma. T1-weighted images after an intravenous gadolinium infusion showed nonhomogeneous enhancement. The enhancing areas of the tumor correlated with areas of tissue vascularity and increased cellular components, because the nonenhanced areas corresponded to the fibrous tissue. Differential diagnoses included subcutaneous tumors with the same or similar MRI appearance such as hemangioma, myxoma, and myxoid liposarcoma.7 The absence of calcifications or ossifications excluded the diagnosis of extraskeletal cartilaginous tumors. Myoepithelial tumors must be considered in the differential diagnosis of soft-tissue tumors of the hand. The rarity of this tumor in the soft tissue has not enabled considerable study of the possibility of malignant degeneration. The additional possibility of
local recurrence and metastasis suggest a complete excision of the tumor and appropriate follow-up examinations of the patient. A preoperative diagnosis based on the MRI characteristics of these tumors may prevent unnecessary biopsy. Received for publication October 30, 2006; accepted in revised form February 27, 2007. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Corresponding author: Mayia Pilavaki, MD, PhD, Mitropolitou Genadiou 20A, 57010, Hortiatis, Thessaloniki, Greece; e-mail: [email protected]. Copyright © 2007 by the American Society for Surgery of the Hand 0363-5023/07/32A05-0014$32.00/0 doi:10.1016/j.jhsa.2007.02.022
References 1. Hornick JL, Fletcher CD. Myoepithelial tumors of soft tissue: a clinicopathologic and immunohistochemical study of 101 cases evaluation of prognostic parameters. Am J Surg Pathol 2003;27:1183–1196. 2. Hamada K, Ueda T, Tomita Y, Yoshikawa H, Hatazawa J. Myoepithelioma of soft tissue originating from the hand: 18 F-FDG PET features. AJR Am J Roentgenol 2006;186: 270 –271. 3. Go JH. A case of soft tissue myoepithelial tumor arising in masticator space. Yonsei Med J 2005;46:710 –714. 4. Kilpatrick SE, Limon J. Mixed tumour/myoepithelioma/parachordoma. In: World Health Organization classification of tumours: pathology and genetics of tumours of soft tissue and bone. Lyon: IARC Press, 2002:198 –199. 5. Kilpatrick SE, Hitchcock MG, Kraus MD, Calonje E, Fletcher CD. Mixed tumors and myoepitheliomas of soft tissue: a clinicopathologic study of 19 cases with a unifying concept. Am J Surg Pathol 1997;21:13–22. 6. Harada O, Ota H, Nakayama J. Malignant myoepithelioma (myoepithelial carcinoma) of soft tissue. Pathol Int 2005;55: 510 –513. 7. Capelastegui A, Astigarraga E, Fernandez-Canton G, Saralegui I, Larena JA. Masses and pseudomasses of the hand and wrist: MR findings in 134 cases. Skeletal Radiol 1999;28: 498 –507.