Osteoid Osteoma at the Proximal Diaphysis of the Fifth Metatarsal.

The foot is rarely the focus of osteoid osteoma, and only a few of those cases are related to the fifth metatarsal. The present case demonstrates that atypical symptoms with suspicious findings on plain radiographs that are not associated with trauma must be analyzed carefully to determine the nature of the lesion and perform the precise treatment to obtain and sustain the cure. A 29-year-old man presented to the outpatient clinic with a 2-year history of chronic pain in the lateral aspect of his left forefoot. The onset was not related to trauma, surgery, local infection, osteomyelitis, or another entity regarding the proximal fifth metatarsal. The patient noted that the pain was aggravated at night and typically subsided with the use of salicylates or other nonsteroidal anti-inflammatory drugs. Initial plain radiographs demonstrated cortical thickening and a lytic lesion at the proximal diaphysis of the fifth metatarsal. Because the pain relief was transient, we suspected an osteoid osteoma lesion, and subsequent magnetic resonance imaging manifested pathognomonic signs of subperiosteal osteoid osteoma. Diagnosis was followed by planning of the surgery that ended the patient's symptoms.