An 89-year-old man with no past medical history of interest consulted for an asymptomatic lesion that had arisen on his left heel 40 years earlier and that had become ulcerated in recent months. Examination revealed an indurated, sessile, skin-colored tumor of 3.5×4cm, with a superficial, exudative brownish-yellow scab (Fig. 1A). Skin ultrasound (18MHz linear probe) revealed a well-defined, heterogeneous hypodermal lesion lying on the fascia. The lesion had a pseudotesticular appearance, with hyperechoic linear tracts internally (Fig. 1B). Peripheral blood vessels were visible on Doppler ultrasound (Fig. 1C). The lesion was completely excised and the histological diagnosis was ancient schwannoma.

Figure 1

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Ancient schwannoma is a rare variant of schwannoma. It is slow-growing, solid, encapsulated lesion, with a prolonged clinical course. Its main characteristic is the presence of degenerative changes on histology. On ultrasound, ancient schwannoma presents as a well-defined lesion that can arise at different depths and with variable degrees of vascularity. Hypoechoic cystic areas, hemorrhages, hyperechoic calcifications, and hyperechoic, cord-like fascicular structures are seen, and anechoic fluid collections may be present. Malignant transformation is very rare, though this may initially be suspected because of the clinical and histological characteristics.