A 45-year-old woman presented in 2018 for recurrent and spontaneously regressing subcutaneous nodules affecting mainly the abdomen and lower extremities (panels A-B). She was diagnosed with primary cutaneous γδ T-cell lymphoma (PCGDTCL) that had infiltrated both dermis and subcutaneous adipose tissue while sparing the epidermis (panels C-D; hematoxylin and eosin stain, original magnification ×25 [C], ×630 [D]). On immunohistochemistry (IHC) cells were T-cell receptor (TCR) δ⁺ (panel E; IHC, original magnification ×630). They were also CD3⁺/CD4^–/CD5^–/CD7^–/CD8^–/CD56⁺/TCR-β^–/granzyme B⁺. Two years later, the patient was hospitalized for recurrent fever, cough, and severe dyspnea. Physical examination showed that ulcerated skin patches affected the lower extremities (panel F). Blood tests revealed pancytopenia with a leukocyte count of 1.2 × 10⁹/L, a hemoglobin concentration of 7.9 g/dL, and a platelet count of 102 × 10⁹/L. In addition, the patient had hyperferritinemia (17 400 ng/mL), hypofibrinogenemia (0.86 g/L), and hypertriglyceridemia (492 mg/dL). A thoracic computed tomography scan showed bilateral ground-glass opacities (panel G). Bronchoalveolar lavage contained a mixture of macrophages that showed hemophagocytosis and atypical lymphoid cells (panel H; May-Grünwald-Giemsa stain, original magnification ×630). By flow cytometry, 79% of lymphocytes were CD3⁺/CD4^–/CD5^–/CD7^–/CD8^–/CD56⁺/TCR γδ⁺ (panel I: population in red). Both β and γ TCR genes were clonally rearranged. Findings were consistent with lymphomatous extension to the lung and secondary hemophagocytic lymphohistiocytosis (HLH). Treatment consisted of high doses of corticosteroids followed by intensive polychemotherapy. Significant clinical and biological improvement ensued.

PCGDTCL represents an aggressive lymphoma, commonly associated with secondary HLH. It might rarely present an indolent clinical course. Patients who present with deep ulcerating lesions tend to have a more aggressive disease than those with a superficial epidermal disease. Lung involvement reflects the frequent dissemination to mucosal and other extranodal sites.