Pseudocarcinomatous change in lymphomatoid papulosis and primary cutaneous CD30+ lymphoma: a clinicopathologic and immunohistochemical study of 6 patients.

ABSTRACT

We report 6 cases of pseudoepitheliomatous hyperplasia (PEH) mimicking squamous cell carcinoma in association with an atypical CD30+ dermal infiltrate. Three patients had lymphomatoid papulosis type A, and 3 patients had cutaneous CD30+ lymphoma. All 6 cases showed histologic evidence of PEH with keratinocyte atypia. In 4 cases there was significant atypia to prompt a diagnosis of squamous cell carcinoma. Three of these received treatment with wide local excision and 2 had been engrafted. Immunohistochemical staining for epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha) showed similar expression in lesional and perilesional skin. Epidermal growth factor receptor (EGFR) expression by the proliferating epithelium was similar to that of the suprabasal adjacent normal epidermis. There was no aberrant expression of EGF, TGF-alpha, and EGFR by atypical lymphocytes. These cases demonstrate that PEH associated with CD30+ lymphoproliferative disease may closely resemble squamous cell carcinoma, thereby leading to inappropriate diagnosis and treatment.