[Clear cell sarcoma of soft tissues. Clinico-pathological and ultrastructural analysis of a case in the head-neck region and a literature review].

BACKGROUND

Clear cell sarcoma of soft tissues (CCSST), even synonymically termed malignant melanoma of soft tissues, is a peculiar malignant tumor with both a prolonged clinical course and a final poor prognosis. Whilst its neuroectodermal histogenesis is most likely, its nosological position is still a matter of debate. Light microscopy (LM), immunocytochemistry (ICC), and electron microscopy (EM) investigations have shown both a melanocytic and schwannian differentiation. Recent findings from cytogenetic analysis documenting a reciprocal translocation between the long arms of chromosomes 12 and 22 [t(12:22)(q13;q12.2)] not seen in cutaneous melanomas nor in other neurogenic sarcomas support CCSST as a distinct entity.

MATERIALS AND

METHODS

A case of CCSST arising in the preparotid region of a young man with a clinical history of two previous surgical interventions was admitted in 1994 and is herein reported. This patient was previously cured twice in different institutions: the first time he was diagnosed with a "melanoma, NOS" of the face and surgically treated 10 years earlier. The second time--meaning one year earlier the admission--this patient was again surgically treated for a local recurrence which was interpreted as a myoepithelioma (clear cell type) of salivary gland origin. A morphological, immunocytochemical, and ultrastructural analysis performed on the last recurrence is herein presented.

RESULTS

On LM the tumor exhibited the classic morphological appearance comprised both of clear and eosinophilic cells with prominent nucleoli, focally containing cytoplasmic granules of melanin pigment. At ICC expression of vimentin and S-100 protein was diffusely demonstrated as well as the melanoma associated antigen HMB-45 was even albeit focally documented.