A 62-year-old man was referred to our department with a 3-month history of a solitary, painless and non-tender nodule located on the lateral aspect of the distal interphalangeal joint of right great toe (Fig. 1). The pricking of the lesion caused drainage of clear and gelatinous materials. His medical and family history were noncontributory. Although the patient had no history of accidental injury, further inquiry revealed that he had had frequent picking habits since the first appearance of the lesion. 2 months prior to his visit, he had had the lesion treated with CO2 laser at a local clinic, but the lesion recurred soon after. The histological examination revealed an intradermal cyst lined by true epidermis and was surrounded by multiple clefts and loose connective tissues (Fig. 2A). The cyst was filled with horny materials arranged in laminated layers.
Fig. 1. Solitary dome-shaped nodule measuring 0.8×0.9 cm on the lateral aspect of distal phalanx of the great toe.
Another cystic structure in the dermis was noticed on further section. The surrounding clefts and the loose connective tissues of the dermis contained abundant hyaluronic acid, which was highlightened with Alcian blue 2.5 (Fig. 2B) and colloidal iron (Fig. 2C). Histologic diagnosis of myxoid cyst and concomitant epidermal inclusion cyst were made. The remaining lesion after the skin biopsy was electrodesiccated and no recurrence has been noted 8 weeks thereafter. cialis canadian pharmacy
Fig. 2. (A) Histopathologic findings show a cystic lesion lined by keratinizing stratified squamous epithelium compatible with epidermal inclusion cyst (H&E stain, original magnification x40). (B, C) Myxoid materials around epidermal inclusion cyst shows the presence of abundant mucin (Alcian blue 2.5 stain (B) and Colloidal iron stain (C), original magnification, x100 (B), original magnification, x200 (C)).