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Leiomyomas within the foot are rare and are difficult to diagnose with only the radiographic and clinical picture. They are benign, slow growing, and very rarely cause pain. We present an unusual case of a dermatology referral patient complaining of callus formation on the plantar aspect of the foot as well as shoe discomfort. The mass was believed to be a lipoma or a fibroma but after surgical excision was found to be a leiomyoma. Our case highlights the rarity of this diagnosis and presents a unique surgical technique utilizing a medial approach to the plantar hindfoot for lesion removal.
The differential is vast and requires a thorough physical exam and focused patient history of presentation including the duration, localization, characterization, and mechanism of injury. The most common etiology is typically plantar fasciitis which has a reported prevalence of .85% in a study performed by the NIH.
When the clinical exam is nondiagnostic, imaging modalities such as radiographs and MRI are utilized for suspected bony and soft tissue pathology respectively. Morton's neuroma and ganglion cysts are the most common benign soft tissue lesions in the foot. More rare pathologies include angiomyoma, giant cell tumor of the tendon sheath, extraskeletal chondroma, lipoma, plantar fibromatosis and hemangioma.
Heel pain confers a broad differential and soft-tissue tumors need to be considered when more common etiologies are ruled out. The plantar surface of the foot is an exceedingly rare location for a leiomyoma. Our authors present one such case of a hindfoot leiomyoma and describe a unique medial approach to the hindfoot for tumor resection.
2. Case report
The patient is a 62-year-old male physician who presented to the dermatology clinic complaining of a mass on the plantar aspect of the left foot that was making his shoe uncomfortable (Fig. 1). Resultant punch biopsy with dermatology indicated an angioleiomyoma. The patient was referred to the foot and ankle orthopedic clinic for further evaluation. He stated that the mass had begun to slowly expand over the last 6 months causing some relative discomfort, but no pain, and denied any history of trauma or insult to the foot.
The patient has a medical history significant for rheumatoid arthritis on adalimumab, hypercholesterolemia, and a remote history of a myocardial infarction. He denies any allergies and is a non-smoker with no reported substance abuse.
On physical examination, his neurovascular exam was intact without any paresthesias. A dime sized mass on the medial plantar aspect of the foot was observed with residual healing from the punch biopsy site. The mass was non-tender and there was no associated Tinel sign. MRI was performed and illustrated a nonencapsulated 3.7 cm by 2.0 cm medial hindfoot plantar mass underlying the medial and central bands of the plantar fascia.
The patient desired to have the mass surgically excised given the recent growth and the associated discomfort with walking. Surgery was performed under general anesthesia with a peripheral nerve block prior to the procedure. The operative extremity was draped and prepped in sterile fashion. The surface of the mass was marked and measured 2 × 2 cm. A transverse incision of approximately 4 cm was made on the medial aspect of the heel. The subcutaneous tissue was bluntly dissected with surgical scissors. A well-defined lipomatous mass was subsequently visualized abutting the plantar fascia and surrounding musculature (Fig. 2). After careful dissection (Fig. 3) two separate masses were excised (Fig. 4). The muscles deep to the fascia were uninvolved and left alone. The site was thoroughly irrigated with sterile saline and the wound was approximated and closed with 2-0 monocryl and wrapped with sterile gauze.
Fig. 2Medial incision into the plantar fascia and intrinsic musculature of the hindfoot.
The specimens, measuring 4 × 2 × 1 and 2 × 2x1 cm respectively, were sent to pathology and described as yellow-pink lobulated soft tissue consistent with a final diagnosis of leiomyoma (Fig. 5).
Fig. 5Higher power shows bland spindle cells with minimal atypia, some with tapered nuclei and cytoplasmic vacuoles (40X).
The patient was discharged with wound dressing and a postoperative shoe. The patient has been using crutches to assist with ambulation. The postoperative course consisted of very little pain. No signs of neuropathy or infection. Follow up at six months demonstrates no clinical recurrence. Patient consent and IRB approval was provided before the drafting of this case report.
3. Discussion
Leiomyomas are common benign tumors composed of monoclonal smooth muscle cells, collagen, and elastin. They can be found anywhere in the body where smooth muscle is present including the eyes, skin, respiratory tract, bladder and uterus.
Literature review has yielded very few cases of hindfoot plantar leiomyomas. Savage et al. presented a case of a symptomatic plantar leiomyoma and subsequent surgical removal through a plantar approach.
Three of which were in the foot and none of them in the hindfoot region. Gajanthodi et al. published a case report of a vascular leiomyoma just proximal to the 2nd web space that was excised directly through a plantar excision.
The author of this case study proposes that a medial incision is a superior approach for accessing soft-tissue tumors that lie deep to the plantar fascia. Benefits are obtained by maintaining the integrity of the plantar fascia and allowing early weightbearing due to the absence of a plantar incision.
In conclusion, leiomyomas are rare benign tumors, especially in the lower extremity. They possess an extremely low risk of malignant transformation to leiomyosarcoma. Curative management involves surgical excision and final diagnosis is dependent on the final histopathological report. Despite this, our case illustrates the importance of the practitioner to keep leiomyoma in mind when evaluating soft-tissue masses of the plantar aspect of the foot. This case also highlights the benefit of a medial approach when resecting tumors deep to the plantar fascia.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.
Declaration of competing interest
The authors have no reported conflict of interests.
Acknowledgements
The authors have no acknowledgements.
References
Riddle D.L.
Schappert S.M.
Volume of ambulatory care visits and patterns of care for patients diagnosed with plantar fasciitis: a national study of medical doctors.
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