The differential diagnosis of CD8‐positive (“type D”) lymphomatoid papulosis

BACKGROUND: Cutaneous CD8(+) CD30(+) lymphoproliferative lesions are difficult to classify and encompass entities that follow a benign course to overt lymphoma. In order to identify histopathologic criteria for lesions in this spectrum, a series of such cases was reviewed. METHODS: Twenty-eight biopsies from 27 patients with CD8(+) CD30(+) cutaneous lymphoid proliferations were evaluated. RESULTS: Seventeen cases were classified as lymphomatoid papulosis (LyP) 'type D', eight as cutaneous anaplastic large cell lymphoma (C-ALCL) and two as CD8(+) mycosis fungoides (MF) with CD30 expression. Features of LyP included spongiosis and/or parakeratosis (90%), epidermotropism by large lymphocytes (90%), with (80%) or without (10%) small lymphocytes; wedge-shaped infiltrate (70%) with perivascular (100%) and interstitial (80%) pattern; and relative uniformity of CD30(+) large atypical cells (90%). C-ALCL was characterized by ulceration (63%), epidermotropism restricted to small lymphocytes (100%), marked density (63%) and pleomorphism (62%) of CD30(+) large atypical cells, and at least focal extension of infiltrate to subcutaneous tissue (88%). CD8(+) CD30(+) MF had vacuolar interface change and a lichenoid pattern (100%). CONCLUSIONS: We concur with previous authors that distinction of CD8(+) LyP from lymphoma in its differential diagnosis is difficult based on histopathology alone. Nonetheless, we propose that certain histopathologic clues may be helpful in this differential diagnosis.