Plantar Epidermoid Inclusion Cyst as a Possible Cause of Intractable Plantar Keratosis Lesions

Abstract

Inclusion cysts are benign lesions that appear as a consequence of traumatic inclusion of epidermal cells into the dermis. They can be painful if they appear under pressure areas, especially the metatarsal heads. We report a case of a 36-year-old woman with an intractable plantar keratosis lesion under the third metatarsal head of 3 years’ duration. Ultrasonography revealed the presence of a subcutaneous mass with a growing epidermoid. It was surgically excised, and pathology confirmed the diagnosis of a plantar epidermoid cyst. All symptoms disappeared after the excision of the lesion. This case should alert the clinician about the existence of keratotic lesions in the metatarsal heads commonly diagnosed and treated as intractable plantar keratosis, although they are not directly derived from metatarsal overload. Some of the lesions could be directly derived from skin problems aggravated by pressure from the metatarsal head. This should be taken into consideration when addressing the management of these lesions. (J Am Podiatr Med Assoc 99(2): 148–152, 2009)