Paraneoplastic pityriasis rubra pilaris as the presenting manifestation of metastatic squamous cell carcinoma.

Pityriasis rubra pilaris (PRP) is a rare idiopathic papulosquamous eruption. Few cases of PAP have been reported in association with malignancies. We report a case of an 83-year-old Caucasian male who presented with recalcitrant paraneoplastic PAP as the presenting manifestation of metastatic squamous cell carcinoma with unknown primary. Treatment with chemotherapy and radiation led to temporary radiologic and symptomatic regression of the cancer as well as resolution of cutaneous findings. This suggests a direct relationship between the PRP and the underlying malignancy in this patient. This case highlights a rare, but important phenomenon in which PAP may act as a harbinger for underlying malignancy.