Hypopyon Sign in Acral Lesions: Dermoscopic Findings of a Patient with Palmoplantar Pustulosis.

Palmoplantar pustulosis (PPP) is a chronic, recurrent inflammatory dermatosis affecting the palms and soles, classified as a form of acral pustular psoriasis. Nail involvement occurs in over half of PPP patients. This report presents a patient with PPP and idiopathic thrombocytopenic purpura who exhibited purpuric plantar and nail lesions. Dermoscopic examination revealed the hypopyon sign in both plantar and nail lesions, as well as centrally located eccrine duct openings within the plantar pustules. The hypopyon sign has been rarely documented, with previous reports limited to lymphangioma circumscriptum and angiosarcoma. This case supports the role of microvascular abnormalities in psoriasis pathogenesis and warrants further investigation into the underlying mechanisms.