[Paraneoplastic pityriasis rubra pilaris in metastatic adenocarcinoma without diagnosable primary]

A 75-year-old woman, without a history of severe illness, developed an erythematosquamous skin disease on hands and forearms. After continued spreading of these cutaneous lesions, she was admitted to hospital, presenting with a generalised desquamating erythrodermia and marked pruritus.

Skin biopsy showed cornocutaneous signs with alternating ortho- and parakeratosis, typical for pityriasis rubra pilaris. Laboratory findings showed a chronic to acute inflammation with leukocytosis, granulocytosis in the differential blood count, raised C-reactive protein in a range from 54.7 to a maximum of 157.2 mg/l and a protein electrophoresis with elevated alpha1- and alpha2-fraction.

The erythrodermia only temporarily receded under systemic therapy with acitretin and prednisolone. The patient developed intermittent septic fever accompanied by reduction or loss of consciousness. The general condition of the patient worsened considerably. Out of a rapidly progressing pleural effusion malignant cells similar to adenocarcinoma were isolated. Because CA15-3 was elevated we conducted an extended search especially for a breast carcinoma, but found only pathologically enlarged axillary, mediastinal and abdominal lymph nodes in conventional X-ray, CT, ultrasound and endoscopic procedures. The patient died from paraneoplastic pulmonary embolism. At autopsy, the widespread metastatic dissemination from poorly differentiated adenocarcinoma was confirmed. A necrosis in the right breast containing tumour cell remnants could probably be regarded as the primary neoplasm. Immunohistochemically no definite proof of breast nor gastro-intestinal carcinoma could be found.

This case presents a rare paraneoplastic cutaneous manifestation as pityriasis rubra pilaris triggered by a poorly differentiated adenocarcinoma. The primary neoplasm could not definitely be identified, neither pre nor post mortem.