Nail Disorders: Diagnostic Clues

Pitting Small depressions on nail plate. Psoriasis (irregular, deep), alopecia areata (geometric grid pattern), eczema (irregular, shallow). Onycholysis Distal separation of nail plate from bed. Psoriasis, fungal infection, trauma, thyroid disease, drug-induced. Subungual Hyperkeratosis Thickening under nail plate. Psoriasis, onychomycosis. KOH/culture to distinguish. Longitudinal Melanonychia Brown-black longitudinal band. Benign melanocytic activation, nevus, subungual melanoma. Hutchinson sign (periungual pigment extension) raises melanoma concern. Beau Lines Transverse depressions reflecting temporary growth arrest. Systemic illness, trauma, chemotherapy. Terry Nails White nail with narrow pink/brown distal band. Hepatic cirrhosis, congestive heart failure, diabetes. Yellow Nail Syndrome Thickened, yellow-green nails with lymphedema and pleural effusions.