Age / Sex : 19 / M

Chief Complaint: Right second toe pain for a year

Discussion

Answer: Giant cell lesion of the small bones (giant cell reparative granuloma)

Findings:

There is a geographic lesion in the base and shaft of proximal phalanx of right second toe. It is hypointense on T1-weighted image and intermediate to hypointense on T2-weighted image. There is adjacent bone marrow and soft tissue abnormal signals. On diffusion-weighted images, it shows impeded water diffusivity. It shows delayed enhancement on dynamic contrast-enhanced images.

Differential Diagnosis:

1. Giant cell lesion of the small bones (giant cell reparative granuloma)


2. Enchondroma


3. Epidermal inclusion cyst

Diagnosis:  

Giant cell lesion of the small bones (giant cell reparative granuloma)

Discussion:

Giant cell lesion of the small bones (giant cell reparative granuloma) is an uncommon benign bone tumor. Giant cell lesion of the small bones occurs in patients in the 2nd and 3rd decades of life and has a predilection for the mandible and maxilla. Nonspecific pain and swelling are the most common clinical manifestations. The second most common location is in the small bones of the hands and feet, which, like the face, are unusual sites for giant cell tumor. Giant cell lesion of the small bones most commonly affects the phalanges of the hand, followed by the metacarpal, metatarsal, carpal, and tarsal bones and the phalanges of the foot. Lysis with expansile remodeling is the most common radiographic appearance of giant cell lesion of the small bones. The cortex is usually thinned but intact, although more aggressive growth with soft-tissue extension has been described. Periosteal reaction is unusual. As in giant cell tumor, these lesions have low to intermediate signal intensity at both T1- and T2-weighted MR imaging. Compared with giant cell tumor, cystic areas (ABC components) are less common and typically constitute only small components. Curettage is used to treat these lesions. Recurrence is seen in 22%–50% of cases. Sarcomatous transformation or aggressive lesional spread has not been described.

References:

1. Murphey MD, Nomikos GC, Flemming DJ, Gannon FH, Temple HT, Kransdorf MJ. From the archives of AFIP. Imaging of giant cell tumor and giant cell reparative granuloma of bone: radiologic-pathologic correlation. Radiographics. 2001;21:1283-1309


2. Fletcher CDM, World Health O, International Agency for Research on C. WHO classification of tumours of soft tissue and bone. 4th ed. Lyon: IARC Press; 2013