Granulomatous slack skin disease (GSS) is a rare disorder characterized by bulky cutaneous lesions and epithelioid and giant cell granulomas with destruction of the dermal elastic tissue. We detail the observation of a 29-year-old man with clinical and histological features of GSS. Pendulous skin tumors were associated with typical clinical and immunohistochemical aspects of mycosis fungoides and with clonal rearrangement of the V gamma T-cell receptor gene in lesional skin. This case report supports cutaneous T-cell lymphoma as a cause of GSS.