Track: Case Reports

Topic: Lymphoproliferative Disorders

Abstract:

Introduction: Primary cutaneous gamma/delta T-cell lymphoma is a rare type of cutaneous T-cell lymphoma consisting of T-cells expressing γ/δ T-cell receptor. Etiologies may include chronic antigen stimulation and immune system dysregulation. This type of T-cell lymphoma carries a poor prognosis.

Methods: Our patient is a 71-year-old male with a one-year history of worsening whole-body rash after receiving the COVID vaccine. Skin findings include diffuse hemorrhagic purpura, scaled erythematous plaques, and eruptive bullae. Dermatology was consulted and a punch biopsy was performed on the right thigh with clinical differential diagnoses including pemphigus vulgaris, pemphigus foliaceus, and herpes simplex infection.

Results: The skin punch biopsy of the right thigh shows a dense lymphomatous infiltrate involving the dermis and subcutaneous tissue. The lymphoma cells are medium to large with mature chromatin. By immunohistochemistry, the lymphoma cells are positive for CD3, CD56, and TCR delta, show loss of other T-cell antigen expression, and are negative for CD20, CD25, CD30, CD123, PAX-5, PD-1, TCL1, TCR beta F1, TdT, and EBER (ISH). Ki67 stain shows a high proliferation rate (90%). Direct immunofluorescence was unremarkable. These findings are consistent with primary cutaneous gamma/delta T-cell lymphoma.

Conclusion: This report documents a rare case of primary cutaneous gamma/delta T-cell lymphoma. Cutaneous T-cell lymphoma may mimic other skin diseases including pemphigus vulgaris, vasculitis, and infection highlighting the importance of clinicopathologic correlation with morphology and immunohistochemistry in arriving at this rare diagnosis.

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Xin Qing, MD/PhD