Pilomatricoma

Case contributed by Ammar Ashraf
Diagnosis certain

Presentation

Painless mass in the right upper posterior chest wall for two months.

Patient Data

Age: 5 years
Gender: Female
ultrasound

There is a small well-defined heterogeneous echogenicity lesion measuring 8 x 13 mm in the superficial subcutaneous soft tissues of right upper posterior chest wall. It has a well-defined hypoechoic rim / capsule. Multiple tiny hyperechoic foci, likely calcifications, are seen in it. There is internal vascularity in the lesion on Doppler ultrasound examination.  These ultrasound features are overall suggestive of a benign pathology and possible differential diagnosis includes sebaceous cyst, dermoid cyst, or epidermal inclusion cyst. 

Case Discussion

This lesion was completely excised and diagnosed as pilomatricoma or calcifying epithelioma of Malherbe on histopathology. No evidence of malignancy was seen.

Pilomatricoma (formerly known as pilomatrixoma or calcifying epithelioma of Malherbe), is a slow growing well-defined benign skin tumour arising from the cortex of a hair follicle. It is commonly seen in patients younger than 20 years 1.

After epidermoid cyst, it is the second most commonly excised paediatric skin mass, accounting for nearly 10% of all superficial masses evaluated by the pathologists 1. Head and neck region (~50% cases), followed by the upper limbs, trunk and the lower limbs are the common sites.  

They are usually diagnosed on the basis of clinical history and physical examination findings with imaging being infrequently used in their diagnosis 1. Ultrasound is usually the initial and only imaging modality used in preoperative evaluation of these tumours 1.

These tumours are primarily treated with complete surgical excision 1.

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