Primary cutaneous CD8-positive aggressive epidermotropic cytotoxic T-cell lymphoma (PCAETL) is a rare, rapidly-growing lymphoid neoplasm with a poor prognosis. It often mimics other skin lymphoproliferative disorders, making diagnosis and treatment challenging. 

An 83-year-old male with a history of advanced-stage Hodgkin lymphoma (in remission), atopic dermatitis on biologic and immunosuppressive therapy, presented with diffuse erythematous skin lesions with focal erosions, refractory to treatment and differing from his prior atopic eczematous dermatitis. Skin biopsies from the chest and extremities revealed epidermal hyperplasia, focal erosion, and intraepidermal and superficial dermal infiltration by medium-to-large atypical lymphoid cells exhibiting vesicular chromatin, prominent nucleoli, and a high mitotic index. Immunohistochemical studies demonstrated that these cells were positive for CD3, CD7, CD8, TIA-1 and CD30 (small subset), with partial loss of CD5. Ki-67 demonstrated a high proliferative index. The atypical cells were negative for both TCR-βF1 and TCR-δ. EBER was negative. 

The clinical, histologic and immunophenotypic findings supported a diagnosis of PCAETL, in which absence of both TCR-βF1 and TCR-δ has been reported.  The absence of TCR-d argued against primary cutaneous gamma-delta T-cell lymphoma, and there was no history of mycosis fungoides to suggest transformed mycosis fungoides. The patient’s immunosuppressed status and lack of response to immunomodulators suggest a possible partial iatrogenic etiology in this case. 

This case highlights the diagnostic complexity of PCAETL, particularly in immunosuppressed patients, and underscores the importance of thorough clinicopathologic correlation. Early recognition is essential for accurate prognostication and appropriate management in this aggressive and rare lymphoma.