Benign Cutaneous Cysts: A Comprehensive Analysis of 1160 cases

Abstract

Background Cysts are common skin abnormalities that are mostly benign; however, sometimes malignant lesions may present clinically as cystic manifestations. Benign cutaneous cysts can be of different morphological types and their diagnosis relies on histological evaluations. The most common mode of treatment is surgical excision, which is curative. Methodology This is a retrospective cross-sectional study conducted at the Department of Histopathology, Chughtai Institute of Pathology, Lahore, Pakistan from 1st January 2020 to 31st December 2022. Non-probability consecutive sampling was done, and all the cases of benign cutaneous cysts were included. All cases were microscopically reviewed by two histopathologists, and variables like age, gender, site of the lesion, and histological diagnosis were noted. The data were analyzed using IBM SPSS Statistics for Windows, Version 29 (Released 2022; IBM Corp., Armonk, New York, United States). Results A total of 1160 recorded cases of benign cutaneous cysts were included. Overall gender distribution revealed males (n=489, 42.1%) and females (n=671, 57.8%). The age range was 3 to 91 years with a mean age of 37.56 ± 16.05 years. The three most common cysts were epidermal inclusion cysts (74.3%), trichilemmal cysts (15.1%), and dermoid cysts (6.3%). Other cysts were uncommon including hidrocystoma (1.9%), steatocystoma (0.3%), verrucous cysts (0.3%), comedones (0.6%), hybrid cysts (0.2%), milia (0.3%), and vellus hair cysts (0.2%). The most common site was back (23.5%) for epidermal inclusion cysts, scalp (74.4%) for trichilemmal cysts, and eye (33.8%) for dermoid cysts. Conclusion Benign cutaneous cysts have a broad morphological spectrum with a wide age range. Epidermal inclusion cysts, trichilemmal cysts, dermoid cysts, and hidrocystoma account for the four most common types. For each of the other cyst type, the prevalence was under 1%. Female gender predominated in epidermal inclusion cysts, trichilemmal cysts, and dermoid cysts while male gender was common in other cysts. Overall majority of the cysts presented in the head and neck area.

Keywords: benign cutaneous cysts; comedones; dermoid cyst; epidermal inclusion cyst; hidrocystoma; steatocystoma; trichilemmal cyst.

Figure 1. Epidermal inclusion cyst

A and B: Cyst showing stratified squamous epithelium with an intact granular layer and flaky keratin in the lumen

Figure 2. Trichilemmal cyst

A: Low-power view of the cyst with abrupt trichilemmal type of keratinization. B: High-power view of the cyst showing stratified squamous epithelium without a granular layer and trichilemmal type of keratin in the lumen.

Figure 3. Dermoid cyst

A and B: Cyst with squamous lining, flaky keratin in the lumen, and pilosebaceous units in the wall.

Figure 4. Eccrine and apocrine hidrocystomas

A: Low-power view of eccrine hidrocystoma. B: High-power view of eccrine hidrocystoma showing flattened to cuboidal lining. C: Low-power view of apocrine hidrocystoma. D: High-power view of apocrine hidrocystoma showing double lining with abundant cytoplasm and apical snouts

Figure 5. Comedone

A: Low-power view of comedones representing multiple small keratin containing cysts. B: High-power view showing closed and open comedones with squamous lining and keratin in the lumen.

Figure 6. Verrucous cyst

A: Low-power view of the cyst showing hyperplastic stratified squamous lining with keratin in the lumen B: High-power view of the cyst showing hyperplastic stratified squamous epithelium with hypergranulosis and keratin in the lumen

Figure 7. Steatocystoma

A: Low-power view of the cyst showing stratified squamous epithelium, sebaceous units in the wall, and empty lumen. B: High-power view of the cyst showing stratified squamous epithelium without a granular layer and prominent surface corrugations.

Figure 8. Vellus hair cyst

A: Low-power view of the cyst showing stratified squamous epithelium and multiple vellus hair admixed with luminal keratin. B: High-power view of the cyst showing stratified squamous epithelium, vellus hair shafts, and keratinous debris in the lumen.

Figure 9. Milia

A: Low-power view showing multiple small keratinous cysts. B: High-power view of the cyst showing stratified squamous epithelium and luminal keratin.