Dermatofibroma Hypocellularity Is Associated With Patient Age: A Retrospective Study of 307 Cases

BACKGROUND: Dermatofibromas are benign fibrohistiocytic neoplasms with numerous histologic variants including the hypocellular variant. Anecdotal observations suggest that dermatofibromas may become increasingly sclerotic and hypocellular with advancing patient age. OBJECTIVE: This study aimed to evaluate the association between patient age and the frequency of hypocellular dermatofibromas. METHODS: A total of 392 dermatofibroma specimens were independently classified by two dermatopathologists into discrete histologic variants: conventional, hypocellular, hemosiderotic/aneurysmal, cellular, lipidized, indeterminate, or other. Only cases with concordant classification between the two dermatopathologists were included in the analysis. Linear regression analysis to be used to evaluate the association between patient age and the prevalence of hypocellular dermatofibromas. RESULTS: Out of the original 392 cases, 307 (78%) specimens received concordant histologic variant classification and were included in the analysis. The frequency of the hypocellular variant was consistently low (0%-18%) in patients in the youngest age groups (10-49 years), increased to 25% in the 50-59 age group, and ranged from 25% to 40% in patients aged 60-89 years old. Linear regression analysis demonstrated a strong positive correlation between patient age and the prevalence of hypocellular dermatofibromas (R-squared = 0.82, p 0.002). LIMITATIONS: The high proportion of shave biopsy specimens (63%) limited assessment of deep dermal histologic features. Another limitation is the inherent subjectivity of categorizing based on cellularity. CONCLUSION: Hypocellular dermatofibromas are increasingly prevalent with advancing age. One possible explanation is that dermatofibromas undergo gradual involution over time, with a corresponding reduction in cellular density as lesions mature.