Background: CD8+ lymphomatoid papulosis is frequently indistinguishable histopathologically from primary cutaneous aggressive epidermotropic CD8+ T-cell lymphoma except for the expression of CD30. However, absent or weak expression of CD30 has been rarely reported in cases of CD8+ LyP. Objective: We aim to study the clinical and pathologic features of cases of CD8+ LyP with no or minimal expression of CD30. Material and Methods: We identified all cases of CD8+ LyP diagnosed in our institution over a period of 10 years. Blinded comparison of clinical and histopathologic features of cases with and without CD30 expression was performed. Results: Among seven cases (four patients) with definitive clinical and histopathologic diagnosis of CD8+ LyP, two cases (29%) had no expression of CD30. These two cases had more prominent epidermotropism, less epidermal ulceration, and less vascular damage relative to cases with CD30 expression and therefore resembled mycosis fungoides and type B LyP. CD5 and CD7 were frequently lost regardless of the CD30 status. Expression of cytotoxic markers was not different between the two groups. In the two cases with lack of CD30 expression, subsequent biopsies showed classic features of CD8+ LyP with strong expression of CD30. Conclusion: CD8+ LyP with lack of expression of CD30 may have distinct histopathologic features that resemble mycosis fungoides and LyP type B. Clinically, they are indistinguishable from their CD30+ counterparts, signifying the importance of clinical correlation to avoid the erroneous diagnosis of lymphoma. Interval biopsies may be needed to establish a definitive diagnosis.
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