Angiocentric T-cell lymphoma of the skin. An aggressive lymphoma distinct from mycosis fungoides.

Among 37 consecutive cases of malignant lymphoma in which the skin was either the only site of disease or one of the prominent sites of initial involvement, 19 cases had a distinctive histological appearance. These cases corresponded to what has been termed "angiocentric lymphoma," and all were found to exhibit a T-cell phenotype either by frozen-section immunohistochemistry or by using monoclonal antibodies reactive in paraffin sections. There were nine men and 10 women; the mean age was 48.2 years. The lesions were nodular and were either ulcerated or had intact skin. One case presented with involvement of one anatomical region of skin, five had involvement of multiple regions of skin, and 13 had concurrent extracutaneous disease. The disease pursued an aggressive course and was not uncommonly resistant to treatment. Histologically, the lymphomatous infiltrate occurred predominantly in the mid to deep dermis with involvement of the subcutaneous layer. The pattern was mainly perivascular and peri-adnexal with or without confluence; the overlying epidermis and papillary dermis were often spared. A prominent feature was invasion of small or large blood vessels by lymphoma cells. Eight cases showed extensive coagulative necrosis of the neoplastic and normal tissues, and 12 cases showed intraneural invasion. The neoplastic lymphoid cells consisted of either a monomorphous population or a variable mixture of small, medium-sized, and large cells with stippled chromatin and distinct nucleoli. Although the nuclei were often irregularly folded, few exhibited a cerebriform configuration. The cytoplasm was pale to clear. These cases exhibit a remarkable histological similarity to the T-cell lymphomas of the nasal/nasopharyngeal region; in addition, there are features that overlap with so-called lymphomatoid granulomatosis of the skin.