A large proliferating trichilemmal cyst masquerading as squamous cell carcinoma

Area of Science:

• Dermatology
• Oncology
• Pathology

Background:

• Proliferating trichilemmal cyst (PTC) is a rare follicular neoplasm.
• Typically occurs on the head and neck region in elderly women.
• Histologic hallmark is trichilemmal keratinization without a granular cell layer.

Purpose of the Study:

• To present a case of proliferating trichilemmal cyst.
• To highlight the diagnostic and management considerations for PTC.
• To emphasize the importance of differentiating PTC from benign trichilemmal cysts due to malignant potential.

Main Methods:

• Case presentation of a 70-year-old female with a scalp mass.
• Clinical examination of the lesion.
• Histopathological analysis of an excisional biopsy specimen.

Main Results:

• A 6 × 5 × 3 cm firm, mobile, painless scalp mass was identified.
• Histopathology confirmed a well-demarcated tumor with lobules of squamous epithelium showing abrupt trichilemmal keratinization.
• No concerning features for malignancy were noted in this specific case, but the potential exists.

Conclusions:

• Proliferating trichilemmal cyst is a benign neoplasm with potential for local aggression and malignant transformation.
• Complete excision is the recommended treatment for all benign PTC variants.
• Accurate histopathological diagnosis is crucial for appropriate management and patient outcomes.