Abstract

Granulomatous slack skin disease is an extremely rare variant of cutaneous T-cell lymphoma (CTCL) as defined by the World Health Organization–European Organization for Research and Treatment of Cancer (WHO-EORTC), with only around 50 cases reported as of 2008. We present a case of a 38-year-old male who presented with flaccid, erythematous, pendulous plaques on the right ventral forearm and in the bilateral groin, as well as erythematous annular plaques on the back and indurated tumors of the back and mid forehead. Dermatopathologic assessment revealed numerous non-necrotizing granulomas and multinucleated giant cells with a sparse lymphoid infiltrate, and in combination with positive T-cell receptor gene rearrangements and immunohistochemistry, led to diagnosis of granulomatous mycosis fungoides (MF). Immunohistochemistry was significant for CD3 and CD5 positivity with loss of CD7. CD30 was negative. Various biopsies of the patient showed a CD4:CD8 ratio of >6:1. The atypical lymphocytes observed were predominantly small to medium with hyperchromatic nuclei and irregular contours. Epidermotropism was observed. Initial diagnosis in these cases is often delayed; clinicopathological correlation is essential for establishing the correct diagnosis, with immunohistochemistry and TCR being necessary components. While isolated granulomatous slack skin disease is considered to be indolent, our patient had overlap with granulomatous mycosis fungoides, which is thought to be more aggressive than non-granulomatous MF.