Trichilemmal cyst

Case contributed by Dr Antonio Rodrigues de Aguiar Neto


This patient presented in the emergency room with dizziness, nausea, palpitations, a little difficulty in speaking, and numbness in the left upper limb. She underwent a CT scan of the skull.

Patient Data

Age: 55 years
Gender: Female

Axial unenhanced CT image shows a well-circumscribed superficial nodule confined to the skin and subcutaneous tissue layer of the right frontal region, with speckled calcifications within the lesion. The cutis and the subcutaneous fat around the nodule are intact without stranding or edema. The lesion does not affect the underlying outer table of the skull vault. It measures 1.1 x 1.3 cm. 

Impression: These findings are consistent with the trichilemmal cyst.

Case Discussion

Trichilemmal cysts or pilar cysts are a solid-cystic lesion arising from the hair follicle 1-4. They are the most common cutaneous nodule in the scalp, with a preference for middle-aged women, and maybe a finding on routine brain imaging 1-4. The trichilemmal cyst is usually benign, but a transformation in a low potential neoplastic form may occur, which results in proliferating trichilemmal cyst 1-4.

This patient presents an asymptomatic noninfiltrating scalp nodule containing calcifications confined within the head's subcutaneous tissue layer of the scalp. Although the definitive diagnosis is through a histopathological study, the CT shows features favoring a trichilemmal cyst diagnosis.

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