CUTANEOUS LEIOMYOSARCOMA

We report the clinical, histopathologic, immunohistologic, and prognos tic findings in 19 patients with cutaneous leiomyosarcoma, eight males and 11 females (mean age, 66 years; age range, 41-93 years). The tumo rs presented mainly as solitary lesions and were located on the head a nd neck (eight lesions), trunk (four lesions), upper extremities (thre e lesions), and lower extremities (four lesions). Histopathologically, two pre-dominant growth patterns were observed: nodular (12 cases) an d diffuse (seven cases). Neoplasms with a nodular growth pattern were characterized by high cellularity and prominent nuclear atypia, and th ey showed conspicuous mitoses, several necrotic cells, and sometimes e xtensive necrotic areas. By contrast, most cutaneous leiomyosarcomas w ith a diffuse growth pattern revealed low cellularity, well-differenti ated smooth muscle cells, inconspicuous mitotic figures, and few or no necrotic cells. Immunohistologic investigations revealed all cutaneou s leiomyosarcomas to express vimentin and smooth muscle actin. Pan-mus cle actin (HHF-35) was also expressed in most cases (15 lesions). Howe ver, only 12 lesions showed positive staining for desmin. Remarkable w as the expression of cytokeratins in five lesions, Clinical follow-up revealed local recurrences in five patients (three cases with nodular pattern and two lesions with a diffuse pattern) after a period ranging from 8 months to 3 years after surgical excision. No distant metastas es have been observed in our series. We conclude that cutaneous leiomy osarcoma with a diffuse growth pattern may constitute a pitfall in his topathologic diagnosis because of the presence of only subtle criteria for malignancy. Cutaneous leiomyosarcoma may show different immunophe notypes, thus emphasizing the importance of using a large panel of ant ibodies (smooth muscle actin, HHF-35, desmin, vimentin, cytokeratins, and S-100 protein) in immunohistologic diagnosis. Cutaneous leiomyosar coma sometimes reveals local recurrences, but it has negligible potent ial for distant metastases.