Clinical History: A 39 year old female patient was referred for MRI with a slowly growing painless soft tissue mass located at the palmar site of proximal phalanx of the thumb. No discoloration of the skin was noted. No neurological deficit was noted.
Imaging Findings: MR Imaging findings revealed presence of a soft tissue lesion around the proximal phalanx of the thumb. The lesion was seen to surround the cortex of the bone. Mild scalloping of the cortical margins were noted at places. The flexor tendon appeared to be displaced anteriorly.
The lesion measured 1.8cm in supero-inferior extent, 1.4cm in transverse dimension and 1.9cm in antero-posterior dimension. It showed low signal intensity on T2WI, T1WI and hyperintense signal on PDFS sequences. Intense enhancement was noted in the lesion on arterial and venous phases. No cystic areas were seen within. No calcifications were seen.Final Diagnosis: Giant cell tumor of tendon sheath. (GCT-TS)