Granulomatous Slack Skin With Lung and Esophagus Involvement: A Case Report and Molecular Analysis

Granulomatous slack skin (GSS) is a rare subtype of mycosis fungoides, and few cases have been known to spread to the blood, lymph nodes, or viscera. We present a case with early dissemination to the lung. A 27-year-old woman, previously healthy, presented with scattered disseminated scaly patches, associated with vulvar and intergluteal firm swelling and groin-skin induration for 1 year. She also reported mild fatigue and breathlessness on moderate exertion. The patient underwent blood tests, skin biopsies, and computed tomography scan. The skin biopsy showed a mildly atypical T-cell lymphoid infiltrate involving the dermis/hypodermis, with focal epidermotropism, associated with a granulomatous infiltrate and elastophagocytosis. The computed tomography scan revealed bilateral ground-glass lung nodular opacities. Positron emission tomography showed an increased signal in the skin and subcutis around the buttocks, inguinal and mediastinal lymph nodes, and lungs. The lung biopsy confirmed a dense T-cell infiltrate with numerous multinucleated giant cells. Subsequently, esophageal involvement was also observed following biopsy. Molecular analyses demonstrated identical T-cell clones in the skin and lung. After 6 cycles of chemotherapy/localized external radiotherapy, the patient had a partial skin response and stable lung disease. A preferred diagnosis of GSS with systemic spread was made based on clinical/histologic/molecular findings, after considering granulomatous mycosis fungoides and peripheral T-cell lymphoma, not otherwise specified. This case highlights the frequent diagnostic difficulty in distinguishing GSS from an inflammatory granulomatous dermatitis. Pulmonary and esophageal involvements are rare in GSS, and the simultaneous presentation of characteristic cutaneous GSS with systemic disease poses an additional classification challenge.