Lymphomatoid Papulosis With T-cell Receptor-Gamma Delta Expression A Clinicopathologic Case-series of 26 Patients of an Underrecognized Immunophenotypic Variant of Lymphomatoid Papulosis

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (gamma delta) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous gamma delta T-cell lymphoma (PCGDTL) or gamma delta mycosis fungoides. We performed a clinicopathologic analysis of the largest series of LyP featuring gamma delta T-cell expression. We identified 26 patients with a diagnosis of LyP with gamma delta T cells from our institutions, as well as through a comprehensive review of the literature, and characterized these cases. Most cases were treated with topical steroids or not treated at all. The majority of cases showed a CD4-CD8+ phenotype and featured at least one cytotoxic marker. Histopathologic features included an intraepidermal or dermal infiltrate with large cells and frequent angiotropism. One case was initially misdiagnosed as PCGDTL, requiring further therapy. Our case series, the largest international cohort of gamma delta T cell predominant LyP cases, confirms marked clinicopathologic heterogeneity that may contribute to misdiagnosis, reasserting the need to identify classic clinical features, CD30+ T-cell components, and markers of cytotoxicity when dealing with this differential diagnosis. A limitation of this study includes somewhat limited follow-up, histologic, and immunophenotypic information for some cases.