When A Runner Presents With Painful Plantar Lesions
Intractable plantar keratosis (IPK). An IPK is a focused, painful lesion located directly beneath a weightbearing portion of the foot, most commonly a metatarsal head. These lesions are discrete callosities with a central area of nucleation that can often extend quite deep with the lesions varying in size from 0.5 cm to 1 cm in diameter.9 These lesions develop on the plantar surface of the foot under prominent metatarsal heads and also under hypertrophic sesamoids. Due to the location of the lesions, pain can limit ambulation and result in an antalgic gait with compensatory changes and the formation of transfer lesions on the plantar aspect of the foot.10
Treatment includes routine debridement, accommodative padding and offloading orthotics. Surgical interventions including metatarsal osteotomy or chondylectomy are options but they often have unpredictable results.11,12
Arsenical keratosis. Arsenic is a naturally occurring metalloid found in the earth’s crust and within numerous ores. Human exposure occurs via contaminated drinking water, agricultural and industrial exposures, and medicinal applications. Arsenical keratoses and arsenic-induced skin cancers are rare in the United States and research has reported only isolated incidences of cutaneous toxicity from environmental or medicinal exposure.13
Arsenical keratoses usually present as multiple lesions and typically occur at sites of friction and trauma, especially on the plantar aspect of the foot, heel and digits. These lesions usually present as small, punctate, non-tender, horny, hard, yellowish, often symmetric, cornlike papules. They range in diameter from 0.2 cm to 1 cm. Lesions may coalesce to form large verrucous plaques.14
Treatment includes surgical excision or destruction of the lesion by cryosurgery, a consultation with an internist for a complete physical examination and a review of systems to determine if an internal malignancy has developed.15,16
Pyogenic granuloma. Also known as lobular capillary hemangioma, pyogenic granuloma is a relatively common benign vascular lesion of the skin and mucosa.17 These lesions appear as solitary glistening red papules or nodules that are prone to bleeding and ulceration.18 Pyogenic granulomas typically evolve rapidly over a period of a few weeks and the precise mechanism for the development of the lesion is unknown. Researchers have postulated that trauma, hormonal influences, viral oncogenes, underlying microscopic arteriovenous malformations and the production of angiogenic growth factors may play a role.19,20
Individuals presenting with a pyogenic granuloma may report a glistening red lesion that bleeds either spontaneously or after trauma. The patient may have a history of trauma preceding the onset of the pyogenic granuloma. Untreated pyogenic granulomas eventually atrophy, become fibromatous and slowly regress. Typically, the solitary lesion is a bright red, friable polypoid papule or nodule ranging from a few millimeters to several centimeters (average size is 6.5 mm). Bleeding, erosion, ulceration and crusting frequently occur. Regressing lesions appear as a soft fibroma.21
Treatment may include the use of topical medications, surgical excision, laser destruction or cryosurgical destruction.22,23
Eccrine poroma. Eccrine poroma is a benign adnexal tumor of the uppermost portion of the intra-epidermal eccrine duct and the acrosyringium.24 Clinically, it appears as a single slow-growing, well circumscribed papule, plaque or nodule that is pink to red in color and has a surface ranging from smooth to verrucous, and is occasionally ulcerated.25 This solitary tumor commonly occurs as a lesion on the plantar aspect of the foot. The clinical diagnosis is often delayed or inaccurate.
One should consider the eccrine poroma in the differential diagnosis of chronic foot lesions. The management of eccrine poroma should be complete excision, including a small amount of grossly normal skin and subcutaneous tissue.