A Mosaic of Pigmentation: Adult-Onset Progressive Cribriform and Zosteriform Hyperpigmentation With a Congenital Pigmentary Lesion

Progressive cribriform and zosteriform hyperpigmentation (PCZH) is a rare acquired pigmentary disorder characterized by unilateral, gradually progressive hyperpigmented macules occurring in the absence of preceding inflammation or systemic abnormalities.Increasing evidence suggests that PCZH may represent a localized manifestation within the spectrum of pigmentary mosaicism.The coexistence of a congenital pigmentary lesion and adult-onset PCZH is rarely described.We report a 24-year-old man who developed gradually progressive, asymptomatic unilateral hyperpigmented macules over the right neck, shoulder, upper back, upper chest, and mandibular region over two years.The lesions respected the midline.Dermoscopy demonstrated a diffuse light-brown reticular pigment network, while histopathological examination showed basal epidermal hypermelanization with increased epidermal melanocyte density, without interface dermatitis, pigmentary incontinence, or nevocytic proliferation.The clinical and histopathological findings were consistent with PCZH.An additional speckled hyperpigmented patch over the contralateral hip, present since birth, was clinically consistent with pigmentary mosaicism.This unusual coexistence of adult-onset PCZH and a congenital pigmentary lesion clinically consistent with pigmentary mosaicism highlights the possible relationship between PCZH and the broader spectrum of cutaneous pigmentary mosaicism.