Cutaneous myoepithelioma: a clinicopathologic and immunohistochemical study of 14 cases. 2004

Jason L Hornick, and Christopher D M Fletcher
Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.

Analogous to mixed tumors of salivary glands (" pleomorphic adenomas" ), cutaneous mixed tumors (" chondroid syringomas" ) contain a ductal (epithelial) component and a variably prominent myoepithelial component. Tumors showing purely myoepithelial differentiation (myoepitheliomas) have only recently been recognized to arise in the dermis, and to date very few cases have been described. To characterize these tumors further, 14 cutaneous myoepithelial tumors were retrieved from the authors' consult files. Eleven patients were male and 3 were female; their median age was 22.5 years (range, 10 to 63 years), and 7 patients were between 10 and 20 years old. Tumor size ranged from 0.5 to 2.5 cm (mean, 1.1 cm). Most tumors arose on the extremities: 6 on the upper limbs, 6 on the lower limbs, and 1 each on the back and nose. Ten tumors were limited to the dermis, and 5 also extended into superficial subcutis. Thirteen tumors were myoepitheliomas (lacking ductal differentiation), and 1 tumor was a myoepithelial carcinoma (exhibiting severe cytological atypia and a high mitotic rate). Histologically, 7 tumors were solid, composed of ovoid to spindled, histiocytoid, or epithelioid cells with no significant stroma, and 7 were predominantly lobulated, with cords or nests of epithelioid, plasmacytoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. One tumor was composed solely of plasmacytoid (hyaline) cells, and 1 exhibited extensive adipocytic differentiation. Among the 13 myoepitheliomas, mitoses ranged from 0 to 6 per 10 high-power fields (HPFs) (mean, 1.5); 8 tumors contained no mitoses. The myoepithelial carcinoma had 39 mitoses per 10 HPFs. By immunohistochemistry, all cases were reactive for epithelial markers (keratins and/or epithelial membrane antigen [EMA]); 13 of 14 (93%) expressed S-100 protein, 10 of 11 expressed (91%) calponin, 11 of 14 (79%) expressed EMA, 9 of 14 (64%) expressed keratins, 8 of 14 (57%) expressed smooth muscle actin, 7 of 14 (50%) expressed glial fibrillary acidic protein, 3 of 11 (27%) expressed p63, and 1 of 6 (17%) expressed desmin. All 5 cases without keratin staining were diffusely positive for EMA, and all of these cases showed a solid growth pattern. Follow-up was available for 8 patients (median follow-up, 40 months; range, 6 months to 9 years); 3 tumors (38%) recurred locally, and 1 tumor (13%) also metastasized to the lymph nodes. The case that resulted in recurrence and metastasis had the highest mitotic rate (6 per 10 HPFs) of the cytologically benign tumors. Follow-up information was not available for the myoepithelial carcinoma. This study suggests that approximately 50% of cutaneous myoepitheliomas are distinctive lesions composed of a solid proliferation of cells with abundant eosinophilic syncytial cytoplasm, which often lack immunostaining for keratin, whereas the remainder demonstrate focally reticular architecture and myxoid stroma or plasmacytoid cells, similar to their counterparts in salivary gland and soft tissue. Whereas most cutaneous myoepitheliomas behave in a benign fashion, there is apparently a significant risk for local recurrence but a low metastatic potential.

UI MeSH Term Description Entries
D008297 Male Males
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D009208 Myoepithelioma A usually benign tumor made up predominantly of myoepithelial cells. Myoepithelial Tumor,Myoepithelial Tumors,Myoepitheliomas,Tumor, Myoepithelial,Tumors, Myoepithelial
D009364 Neoplasm Recurrence, Local The local recurrence of a neoplasm following treatment. It arises from microscopic cells of the original neoplasm that have escaped therapeutic intervention and later become clinically visible at the original site. Local Neoplasm Recurrence,Local Neoplasm Recurrences,Locoregional Neoplasm Recurrence,Neoplasm Recurrence, Locoregional,Neoplasm Recurrences, Local,Recurrence, Local Neoplasm,Recurrence, Locoregional Neoplasm,Recurrences, Local Neoplasm,Locoregional Neoplasm Recurrences,Neoplasm Recurrences, Locoregional,Recurrences, Locoregional Neoplasm
D002648 Child A person 6 to 12 years of age. An individual 2 to 5 years old is CHILD, PRESCHOOL. Children
D005121 Extremities The farthest or outermost projections of the body, such as the HAND and FOOT. Limbs,Extremity,Limb
D005260 Female Females
D005500 Follow-Up Studies Studies in which individuals or populations are followed to assess the outcome of exposures, procedures, or effects of a characteristic, e.g., occurrence of disease. Followup Studies,Follow Up Studies,Follow-Up Study,Followup Study,Studies, Follow-Up,Studies, Followup,Study, Follow-Up,Study, Followup
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000293 Adolescent A person 13 to 18 years of age. Adolescence,Youth,Adolescents,Adolescents, Female,Adolescents, Male,Teenagers,Teens,Adolescent, Female,Adolescent, Male,Female Adolescent,Female Adolescents,Male Adolescent,Male Adolescents,Teen,Teenager,Youths

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