Relapsed hepatosplenic T-cell lymphoma heralded by a solitary skin nodule.

Hepatosplenic T-cell lymphoma (HSTL) represents a rare form of peripheral T-cell lymphoma composed of lymphocytes that typically express the γδ T-cell receptor. This form of lymphoma rarely involves the skin. We report the case of a 23-year-old man with a history of HSTL that was presumed to be in remission who presented with a solitary cutaneous nodule. Skin biopsy showed an atypical lymphocytic infiltrate arranged in a perivascular and periappendageal pattern with associated vacuolar epidermal interface change. The constituent T cells expressed CD2, CD3, CD7, CD8, β-F1, γδ T-cell receptor, Tia-1 and granzyme B. The cells lacked the expression of CD4, CD5 and CD56. Fluorescence in situ hybridization (FISH) showed a characteristic chromosomal abnormality, namely isochromosome 7q, which confirmed the diagnosis of cutaneous HSTL. On restaging his disease, widespread progression was noted. To our knowledge, this report provides the first detailed account of cutaneous involvement by HSTL. We show the novel utility of FISH to identify isochromosome 7q in the lesional skin of HSTL patients.