Lymphomatoid papulosis with pseudocarcinomatous hyperplasia in a 7‐year‐old girl: a case report

Lymphomatoid papulosis (LyP) belongs to the group of cutaneous CD30+ lymphoproliferative disorders. Pseudocarcinomatous hyperplasia has rarely been reported in patients with LyP. In this report, we describe a case of LyP presenting as pseudocarcinomatous hyperplasia. The patient was a 7‐year‐old girl who presented with a recurrent papulonodular eruption on her face and trunk for 2 months. Histopathologic examination revealed an irregular growth of hyperkeratotic epidermis into the whole dermal layer with marked nests of squamous cells in the background of diffuse atypical lymphoid cells, eosinophils and neutrophils. The large atypical cells were positive for CD30 and CD3, but negative for CD4, CD5, CD8, CD20 and CD56. A TCR‐γ clone was identified by polymerase chain reaction (PCR). The correct diagnosis in cases of LyP with overlying pseudocarcinomatous epithelial hyperplasia can be very difficult both clinically and histopathologically. Clinical and histopathologic characteristics should be integrated to avoid an erroneous diagnosis of squamous cell carcinoma or keratoacanthoma.