Abstract

Cutaneous lymphoid proliferations which exhibit epidermotropism are typically of T-cell lineage. For those demonstrating a predominance of intraepidermal CD8+ cells, the differential diagnosis encompasses a number of entities with behaviors ranging from indolent to malignant. On the latter end of this spectrum, primary cutaneous CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (PCAETL) is characterized by an aggressive clinical course and short median survival. PCAETL is defined by both a predominance of epidermotropic CD8+ T-cells along with the expression of cytotoxic markers. Here, we present the case of a 69-year-old male who presented with a full body crusted rash that had progressed over the past month. His lesions were described as burning and extremely pruritic. An outside biopsy showed eosinophilic spongiosis. However, a second inhouse biopsy demonstrated an atypical epidermotropic and folliculotropic lymphoid proliferation. Immunohistochemistry characterized the infiltrate as a T-cell population with a predominance of CD8+ cells expressing cytotoxic markers. Additional studies identified a clonal gamma T-cell receptor rearrangement. The overall findings were consistent with PCAETL. The patient had a complicated hospital course and was eventually discharged to home hospice. We contrast the findings in this case with examples of other, more indolent CD8+ epidermotropic lymphoid infiltrates that we have encountered: CD8-positive mycosis fungoides (MF), type D lymphomatoid papulosis (LyP), and the indolent CD8-positive lymphoid proliferation of the ear and face. We discuss our diagnostic approach, as well as the defining diagnostic features, potential pitfalls, and the natural clinical course of these various entities.