Track

Abstract

Nodal T-follicular helper cell lymphoma, angioimmunoblastic type (nTFHL-AI), is a peripheral T-cell lymphoma with a T-follicular helper phenotype that most often presents with lymphadenopathy and systemic disease. However, cutaneous manifestations are present in up to 50% of cases, and may rarely be the initial presentation.

We report a 72-year-old man with a 4-month history of recurrent, firm, red–violaceous subcutaneous nodules on the trunk and extremities. Initial shave biopsy revealed a mixed dermal histiocytic infiltrate suggestive of an arthropod bite reaction. Lesions progressed over months, prompting punch biopsy, which showed a dense nodular dermal and subcutaneous lymphohistiocytic and plasmacytic infiltrate with a subset of large atypical lymphoid cells, scattered eosinophils and focally incorporated germinal centers. Immunohistochemistry demonstrated CD3+, CD4+, PD-1+, ICOS+, and CXCL13+ T-cells, variable CD10 and BCL6 expression, and moderately increased Ki-67 proliferation rate. An associated EBV-positive B-cell proliferation with kappa light chain restriction was also present. Both T- and B-cell receptor gene rearrangement studies demonstrated clonality. Findings supported cutaneous involvement by nTFHL-AI with associated EBV-positive B-cell lymphoproliferative disorder.

This case illustrates some of the potential diagnostic challenges of cutaneous nTFHL-AI, where early biopsies may mimic reactive dermatoses. Expanded immunohistochemical panels for TFH markers, EBV studies, and molecular clonality analysis may assist in diagnosis. Interval re-evaluation in the setting of progressive symptoms may also be critical for obtaining a diagnostic specimen as in this case. Awareness of this presentation is essential for timely staging and management given the aggressive clinical course and ~50% 3-year overall survival rate.