Acrokeratosis Paraneoplastica (Bazex Syndrome): A Systematic Review and Quantitative Analysis of 106 Cases.

BACKGROUND: Acrokeratosis paraneoplastica (Bazex syndrome) is an obligate paraneoplastic dermatosis characterized by symmetrical acral psoriasiform lesions and nail dystrophy. METHODS: We conducted a PRISMA-compliant systematic review of 99 publications (89 case reports, 10 case series) describing 106 patients to re-examine the syndrome's epidemiology, oncologic associations, clinical features, treatment response, and prognosis. RESULTS: The mean age at onset was 63.5 years (median: 62.5 years; interquartile range (IQR): 57-70 years); men comprised 72.6% (n = 77; 95% CI, 63.5-80.2%), yielding a male-to-female ratio of 2.7:1. Squamous cell carcinoma accounted for 51.9% (55/106; 95% CI, 42.5-61.2%) of associated malignancies, followed by adenocarcinomas (18.9%; 95% CI, 12.6-27.4%) and hematologic neoplasms (8.5%; 95% CI, 4.5-15.4%). Cutaneous lesions preceded the cancer diagnosis in 80.6% (83/103) of patients with reported chronology, with a median lead-time of 5 months (IQR 2-10 months). Nail involvement was documented in 73.6% (78/106). Following oncologic therapy, complete cutaneous clearance occurred in 36.8% (95% CI, 28.2-46.3%) and partial improvement in 30.2% (95% CI, 22.3-39.5%) of cases. In univariable analyses, distant metastasis (p = 0.021) and an aerodigestive primary site (p = 0.026) were nominally associated with reported mortality, although neither remained significant after multiple-comparison correction. CONCLUSION: Bazex syndrome should be suspected in patients presenting with treatment-resistant acral psoriasiform lesions and nail dystrophy, prompting rigorous malignancy screening.