Cowden syndrome: report of two cases with immunohistochemical analysis for PTEN expression.

Cowden syndrome (CS) is a rare autosomal dominant disorder characterized by multisystem hamartomatous growths and carcinomas. CS is linked to germ line mutations in PTEN (phosphatase and tensin homolog) located on chromosome 10q23.3. PTEN acts as a tumor suppressor to negatively control cellular growth and survival via the PI3K/AKT signaling pathway. Presented here are 2 patients with multiple, persistent, and asymptomatic papules on the face and the upper body, histologically consistent with trichilemmomas. Diagnosis of CS was made in each case based on the established diagnostic criteria and confirmed using immunohistochemistry directed against PTEN. We propose that the assessment of PTEN expression levels can aid in the identification of patients with CS.