Philadelphia, Pennsylvania: A neurilemmoma is a benign peripheral nerve tumor that may manifest clinical as paresthesias and numbness/tingling along the potentially affected nerve. Cutaneous manifestations especially without any associated neurologic symptoms are rare and has not been reported in the literature. Majority of these tumors present on the trunk, neck and head, but account for approximately 4% in the foot. More than 80% of the neurilemmonas found on the foot typically present on the ankle and heel, but rarely on the dorsal foot.
S. Mateen and J. Pontious presents a case study of a 62-year old female who presented to the office with a relatively benign soft tissue lesion on her right foot. She underwent a local punch biopsy and subsequently the pathology report revealed a tumor consistent with a neurilemmoma. This is a simple case report that demonstrates a relatively benign presentation with an unusual diagnosis.
This is a case of a 62-year old female with a past medical history of well controlled type two diabetes mellitus who presented with a complaint of a small painful lesion on the instep of her right foot. When the patient arrived she was seeking a second opinion after continued pain. The patient personally did not have any history of cancer, however, the patient was concerned with the appearance of her foot lesion given her family's history of malignant melanoma.
On her clinical examination, she had a mildly raised well-circumscribed small lesion on the instep of her right foot that was hypertrophic and tan, measuring 0.5 cm x 0.5 cm. She had mild pain on palpation without any associated neurologic symptoms. Based on the appearance, a punch biopsy was done to the patient for further clarity of her diagnosis.
The pathology results demonstrated a well-circumscribed neoplasm with a thin zone of compressed collagen. The composition of the specimen was a mix of loose stroma and myxoid with scattered spindle cells. There were other areas of spindle shaped cells with an acellular zone [Verocay bodies]. The results were consisted with a neurilemmona (Schwannoma). After following up in clinic one week after the biopsy was performed, the patient had very mild pain from the punch biopsy site. The sutures were removed from her right foot and the patient was told only to follow up as needed.
The authors opined that - there have been some isolate case reports of neurilemmomas in the foot and ankle, however, this case report represents a unique clinical finding in the medial instep of the foot without associated neurologic symptoms. Accurate and thorough history and physical examination is essential for proper diagnosis and treatment.
Further reading:
A rare cutaneous manifestation of a neurilemmoma of the foot: A case report Sara Mateen, Jane Pontious.
Foot & Ankle Surgery: Techniques, Reports & Cases 1 (2021) 100100
https://doi.org/10.1016/j.fastrc.2021.100100