99mTc/Tricine/HYNIC ubiquicidin 29-41 uptake in a giant cell tumor of the hallux: insights into the importance of time-activity curve analysis for accurate scan interpretation.

A 37-year-old man presented with swelling and erythema in the left first toe after a prior trauma, suspicious for osteomyelitis. X-ray and computed tomography (CT) scans revealed a radiolucent lesion with cortical disruption. A 99mTc/tricine/HYNIC ubiquicidin 29-41 (UBI) scintigraphy showed increased uptake but a non-accumulative time-activity curve, indicating a false positive for infection. Surgical excision confirmed a giant cell tumor. This case underscores the importance of integrating time-activity curve analysis with target-to-reference ratios in [99mTc]Tc-UBI scintigraphy for accurate diagnosis.