An osteoid osteoma coexisting with a ganglion cyst in the fifth metatarsal head: A rare case report.

Osteoid osteoma is a small, benign, but intensely painful bone tumor that usually arises in the diaphysis or metaphysis of long bones such as the femur, tibia, or humerus. Its occurrence in the metatarsal bones is exceedingly rare. Even more unusual is its coexistence with a ganglion cyst, a benign cystic lesion commonly seen around joints or tendon sheaths. The overlapping symptoms of these 2 entities can mask the typical presentation of osteoid osteoma and make diagnosis challenging. We describe a 70-year-old man who presented with nocturnal pain localized to the head of the fifth metatarsal, which was temporarily relieved by nonsteroidal anti-inflammatory drugs. Magnetic resonance imaging (MRI) unexpectedly revealed an osteoid osteoma associated with a ganglion cyst in the same region. The patient underwent curettage and cauterization, leading to complete resolution of pain within 2 weeks. This rare presentation, particularly given the patient's age of 70 years, underscores the need to maintain a high index of suspicion for osteoid osteoma, even when it occurs in atypical sites and in the presence of concurrent benign lesions such as a ganglion cyst. Recognizing this unusual coexistence can help avoid misdiagnosis and ensure timely, effective treatment.