Metatarsal coalition with pseudarthrosis mimicking bone tumor: two case reports and literature review

Metatarsal coalition is an extremely rare congenital anomaly. Its complication with pseudarthrosis is even more exceptional and may present as a palpable dorsal mass or chronic pain, often mimicking a bone tumor. Awareness of this condition is essential for accurate diagnosis and to avoid unnecessary biopsies or overtreatment. We report two cases of metatarsal coalition complicated by pseudarthrosis. The first case involved a 25-year-old woman with a 7-year history of a mildly painful dorsal foot mass. Imaging revealed a coalition between the first and second metatarsals, along with pseudarthrosis formation. The second case involved a 54-year-old man with long-standing dorsal foot pain due to coalition between the third and fourth metatarsals. Both patients underwent surgical excision, and histopathology confirmed fibro-osseous pseudarthrosis. Postoperative recovery was uneventful, with complete resolution of symptoms. During clinical follow-up at 41 and 21 months, respectively, no signs of recurrence were observed. These cases highlight an uncommon presentation of metatarsal coalition mimicking bone neoplasms. Timely recognition and appropriate diagnostic workup are critical to avoid misdiagnosis and unnecessary intervention.