Cutaneous epidermal cysts are common lesions comprising approximately 85-90 percent of all excised cysts.₁ Malignant change is extremely rare and it should be suspected in patients with atypical or larger cysts or a history of cyst recurrence.₂ Hence, we report this case of epidermal cyst in anterior chest wall with carcinoma in situ, with a short history of only one month and possibly is of the smallest size documented in the English literature. A 38 year old female presented to surgical OPD with a tiny subcutaneous swelling of 1 cm diameter size on the anterior chest wall, since 1 month. The swelling was non- tender, soft and movable. The diagnosis of epidermal cyst was made clinically. Surgical excision of the cyst was performed with about 1 cm of surrounding skin. On gross examination revealed a cystic lesion about 0.6 cm in diameter in upper dermas with unremarkable overlying skin. On cutting open the cyst, it was filled with whitish gelatinous material. Microscopically, a cyst was seen lined by stratified squamous epithelium. The squamous cells were seen proliferating in tiny nests (Figure 1). In one focus, proliferating cells were involving full thickness of the lining with peripheral palisading. Moderate atypia was noted (Figure 2).

Figure 1

Figure 1: showing epidermal cyst with proliferation of squamous cells in nests (H&E X 120)

Figure 2

Figure 2: showing epithelial atypia in the squamous cells (H&E X 256).

A diagnosis of epidermal cyst with carcinoma in situ was offered. There was no history of any lymph node enlargement anywhere or any other skin nodule.

Epidermal cysts are commonly encountered in surgical practice. Malignant change is extremely rare₁. A compilation of the major large series by Ana Lucia et al revealed 72 carcinomas in 3300 cysts examined, giving an incidence of 2.2%. Others have been sporadic case reports₂. In different reports, different sizes of epidermal cysts have been shown to have a malignant potential with sizes as small as 1.1 cm³. Malignant change should be suspected in atypical or large cysts or in a history of cyst recurrence₂. But to our best knowledge, malignant change in size as of our case has not been described previously in the literature. The tendency for the cyst to become malignant may increase as the patient grows older. We report a rare case of epidermal cyst of 0.5 cm size with carcinoma in situ in a 38year old female presented with a short history of only one mouth. We, therefore, emphasize importance of subjecting all resected skin cystic specimens to microscopic examination.

Correspondence to

Dr. Kim Vaiphei # 127/C, Sector 24/A, Chandigarh- 160023. Fax : 0172- 744401 E-mail: kimv@glide.net.in nalini203@rediffmail.com