Granulomatous variants of cutaneous T-cell lymphoma. The histopathology of granulomatous mycosis fungoides and granulomatous slack skin.

Granulomatous mycosis fungoides is an unusual histologic variant of mycosis fungoides, a condition that is ordinarily indolent. Granulomatous slack skin, like granulomatous mycosis fungoides, shows epidermotropism, granulomatous inflammation, a clonal T-helper cell population, and progression to systemic lymphoma in some cases. Unlike granulomatous mycosis fungoides, it is characterized clinically by bulky, pendulous skin folds. The similarities between the two conditions prompted us to compare the histologic features. We reviewed 24 biopsies from 10 patients with granulomatous mycosis fungoides. These showed several distinct histologic patterns, including three cases that mimicked granuloma annulare. We also reviewed biopsy specimens from four patients with granulomatous slack skin. These specimens had a more stereotypic appearance, with permeation of the entire dermis and subcutis by lymphocytes, marked epidermotropism, and a more even distribution of granulomas and giant cells within the infiltrate. Biopsies of fully developed lesions of granulomatous slack skin showed elastolysis involving the full thickness of the dermis--a feature not seen in any of our granulomatous mycosis fungoides cases. Biopsy specimens from granulomatous mycosis fungoides and granulomatous slack skin may be mistaken for nonneoplastic granulomatous dermatitides, but they can usually be distinguished from these by the presence of epidermotropism or atypical lymphocytes. Because several of our patients with granulomatous mycosis fungoides died after courses of unremarkable length, it seems unlikely that the presence of granulomas is invariably correlated with a more benign course than nongranulomatous mycosis fungoides.