Introduction: Fibro-osseous pseudotumor of the digit is a rare benign lesion of subcutaneous tissue that typically arises in the parabone site of the proximal phalanx in young adult females. The lesion is histopathologically characterized by fibroblastic proliferation and osteoid formation. Good prognosis following complete surgical excision of the tumor has been reported, with a very low recurrence rate and no reports of malignant transformation. Despite its benign clinical behavior, the lesion can be mistaken for a malignant neoplasm, such as an extraskeletal or parosteal osteosarcoma, in case of rapid growth, thereby rendering the diagnosis challenging. Patient concerns: We report the case of a 30-year-old right-handed male who presented to our hospital with a rapidly growing mass on the dorsal aspect of the right little finger. Diagnosis: The patient was suspected to have soft tissue tumor of the little finger. The lesion could be considered a malignant tumor on the basis of clinical findings. Interventions: The patient underwent surgery for exploration and excision of the mass. Outcomes: The excised mass was diagnosed to be fibro-osseous pseudotumor of the digit upon histological assessment. Postoperatively, the wound healed without complications. At postoperative 6 months, there were no signs or symptoms of recurrence, and the patient returned to his premorbid functional status. Conclusion: Following the detection of a soft tissue mass with clinicopathological features of pseudomalignancy in the digit, clinicians should consider fibro-osseous pseudotumor of the digit as a possible diagnosis, thereby avoiding unnecessary aggressive surgery.
