Atypical Presentation of Tenosynovial Giant Cell Tumor on the Hallucal Flexor Tendon Sheath: A Case Report.

ABSTRACT

Tenosynovial giant cell tumor (TGCT) is a rare type of neoplasm that may be locally aggressive but is most often benign and can be divided into two subtypes localized and diffuse. It tends to develop in the joints, bursae, and tendon sheaths primarily in the digits of the hand and less commonly in the forefoot. This soft-tissue mass has many possible differential diagnoses, including lipoma, ganglion cyst, plantar fibroma, and various sarcomas; surgical excision is usually indicated to reach a definitive diagnosis and rule out malignancy. We report a rare case of a 30-year-old woman with atypical plantar hallucal pain and a palpable mass on the plantar lateral aspect of the left hallux. Surgical excision and histopathologic evaluation confirmed a TGCT of the left hallucal flexor tendon sheath. Although it bears clinical resemblance to several other soft-tissue masses, TGCT has numerous pathognomonic features evident with advanced imaging and histologic analysis that help the physician obtain an accurate diagnosis and proceed with appropriate treatment.