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

BACKGROUND: 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. CASE PRESENTATION: 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. CONCLUSIONS: 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.