Epidermal Cysts: A Clinicopathological Analysis with Emphasis on Unusual Findings

Abstract

Background: Epidermoid cysts, one of the common benign intradermal or subcutaneous tumors commonly result from the trauma to the pilosebaceous unit in the hair bearing area. In areas without hair, these cysts are considered implantation and proliferation of squamous epithelium into the dermis due to injury.

Aims: The aim is to evaluate the clinicopathological details with emphasis on unusual findings related to epidermoid cysts.

Study design: This is a retrospective cross-sectional study carried out over 2 years.

Materials and methods: A total of 103 cases of epidermoid cysts were included in the study. The clinical details such as age, gender, sites, and dimensions were noted. The histopathological findings were evaluated and correlated with the clinical findings.

Results: The highest incidence was observed in the age group of 21-30 years (23.3%, 24/103) and the most common affected region was the head and neck region (32%, 33/103). The size of cysts ranged from 0.3 to 9 cm in diameter with a mean of 2.1 cm. The unusual sites observed in this study were four at the left sole, two at right sole, two at prepuce, and one each at the right finger, left palm, and oral cavity. Histopathological findings included rupture of epidermoid cysts with giant cell reaction, melanin pigmentation, and association with other pathologies such as keloid and lipoma.

Conclusion: Epidermoid cysts are common benign intradermal or subcutaneous tumors, but they can have unusual presentations and histopathological findings. Epidermoid cysts need early diagnosis and treatment as they can cause cosmetic and functional impairment.

Keywords: Epidermal inclusion cyst; implantation; pilosebaceous unit; squamous epithelium.

Figure 1

Age wise distribution of epidermoid cyst

Figure 2

Region wise distribution of epidermoid cyst with male and female numbers

Figure 3

(a) Vague swelling over the sole of left foot. (b) X-ray showing well-defined oval radiopaque lesion in heel pad region below calcaneum. (c) Vague swelling on the left leg. (d) Cystic swelling over right palm

Figure 4

(a) Epidermoid cyst lined by stratified squamous lining having granular layer with laminated keratin material (H and E, ×400). (b) Epidermoid cyst showing giant cell (H and E, ×400). (c) Rupture epidermoid cyst with giant cell reaction (H and E, ×400). (d) Epidermoid cyst with dense melanin pigment containing macrophages (H and E, ×100, inset: Masson–Fontana, ×100). (e) Epidermoid cyst with dense melanin pigment containing macrophages (H and E, ×400). (f) Epidermoid cyst with keloid (H and E, ×100)