Benign Pilomatricoma With Osseous Metaplasia: A Rare Case

Area of Science:

• Dermatology
• Pathology
• Oncology

Background:

• Pilomatricomas are benign skin neoplasms originating from hair matrix cells.
• Calcification is common, but ossification (osseous metaplasia) is a rare occurrence.
• Osseous metaplasia in pilomatricomas is poorly documented, with limited reported cases.

Observation:

• An 87-year-old female presented with a long-standing, hard scalp nodule initially misdiagnosed as an epidermal cyst.
• The lesion exhibited a 17-year history, with recent bleeding and ulceration.
• Clinical presentation included a 2x1cm nodule with hardened yellow material on the occipital scalp.

Findings:

• Histological examination revealed a partially ulcerated dermal lesion with keratin islands and ghost cells.
• Key findings included foreign body granulomas, mature lamellar bone formation, and calcification.
• The diagnosis confirmed benign pilomatricoma with osseous metaplasia, excluding malignancy.

Implications:

• This case underscores the diagnostic challenges in differentiating pilomatricomas from other benign skin masses.
• Accurate histological analysis is crucial for identifying rare variants like pilomatricoma with osseous metaplasia.
• Recognizing this rare entity aids in appropriate patient management and avoids unnecessary interventions for benign conditions.