Pseudotumoral appearance of a ruptured epidermal cyst in the foot

Abstract

We present a case of keratin granuloma due to a ruptured epidermal cyst, occurring in the foot, in a 52-year-old woman. The patient presented with a history of a slow-growing lump in the web space of the foot that had been present for over a year. Imaging appearances suggested a soft tissue neoplasm. Clinical presentation, radiological features and histopathological findings are described, and the relevant literature is reviewed.

Ruptured epidermal cyst mimicking cutaneous melanoma on F-18 FDG PET/CT

“…With a ruptured EIC, there is spillage of keratin in the dermis triggering “foreign body” granulomatous reaction and hypervascularity. These changes may exhibit complex cystic/septated features and heterogeneous or rim contrast enhancement on CT and MR simulating soft tissue neoplasm with necrotic component [ 8 , 9 ]. Sonography may show multilobulated lesions with increased ultrasound Doppler flow signal [ 1 , 5 , 7 ].…”

Pseudotumoural soft tissue lesions of the foot and ankle: a pictorial review

“…Ruptured epidermoid cysts tend to present as multilocular lesions, with enhancement of the cyst wall due to fibrosis and giant-cell reaction to keratin, possibly mimicking malignancy [29]. …”

Palmoplantar epidermoid cysts: two cases and brief review of the literature

“…In most cases of ECs of the sole, the presence of parakeratosis and a focal absence of granular layer were found at least at the upper portion of the cyst wall [11]. When ECs rupture, the cyst contents are released into the dermis, with resultant keratin granuloma formation that exhibits foreign-body giant cells and chronic inflammatory cells [12].…”