Morphological spectrum of pilar cysts

Area of Science:

• Dermatopathology
• Surgical Pathology

Background:

• Skin cysts are frequently excised, often misdiagnosed clinically as sebaceous cysts.
• Histopathological examination is crucial for accurate cyst classification based on keratinization type.
• Trichilemmal (pilar) cysts present as both non-neoplastic and neoplastic entities.

Purpose of the Study:

• To determine the incidence of trichilemmal cysts in surgical pathology.
• To document the diverse morphological presentations of these cysts.
• To emphasize the diagnostic challenges and importance of recognizing specific keratinization patterns.

Main Methods:

• Retrospective review of histopathology files over a 6-year period.
• Inclusion criteria focused on cases coded as pilar cysts.
• Analysis of morphological features for accurate classification.

Main Results:

• Eight cases (5.75%) demonstrated trichilemmal differentiation.
• One case each of proliferating trichilemmal cyst and malignant proliferating trichilemmal tumor were identified.
• The majority of cases occurred in females, predominantly on the scalp.

Conclusions:

• Trichilemmal tumors are rare histopathological findings.
• Misdiagnosis can occur due to unfamiliarity with the characteristic keratinization.
• Accurate diagnosis relies on recognizing the unique histopathological features of trichilemmal lesions.