Paraneoplastic pityriasis rubra pilaris in association with prostate carcinoma: A case report and literature review

Pityriasis rubra pilaris (PRP) is a chronic papulosquamous disorder of unknown etiology, characterized by reddish orange scaly plaques, islands of sparing, palmoplantar keratoderma, and keratotic follicular papules. The disease can be acquired or inherited, being divided into 5 categories: classic adult type, atypical adult type, classic juvenile type, circumscribed juvenile type, and atypical juvenile type. More recently, an HIV-associated type has been added to this classification. The cases of PRP associated with malignancy are unusual. We present a case of a 58-year-old man, with the typical clinical aspect of PRP with a four-month onset of the disease. The histopathological and dermatoscopical findings confirmed the PRP diagnosis. The routine laboratory results were in normal limits, except the number of eosinophils, which was elevated and the number of lymphocytes, which was lower. After a thorough examination within a hematological consultation, the cause of hypereosinophilia remained unknown. An imagistic examination was performed and a prostate hypertrophy was noted. The prostate-specific antigen (PSA) level was found to be increased. The urologic consultation based on clinical, imagistic and microscopic features diagnosed an early stage prostate carcinoma. The conclusion was a paraneoplastic PRP in association with prostate carcinoma. The search in international databases revealed twelve published cases regarding the association of PRP with malignancies. The presented case represents a rare coexistence of PRP with malignancy, particularly with prostate carcinoma, and indicates that PRP can occur as paraneoplastic dermatosis, heralding a malignancy. This case is the first one to present PRP associated with prostate carcinoma. Nonetheless, in the authors' opinion, PRP can be considered a paraneoplastic syndrome; therefore, tumor screening is mandatory in cases presenting this disease.