CLINICAL HISTORY:
34 year old female with stable left rib mass.
Postop Diagnosis: Possible fibrous displasia, rule out tumor.
Operative Procedure: FNA

FINAL MICROSCOPIC DIAGNOSIS:

Left rib, Fine needle aspirate:  Benign spindle cell proliferation and giant cells.

Comment:  The smears show a spindle cell proliferation and giant cells.  These findings are nonspecific in bone lesions and the differential diagnosis includes fibrous dysplasia, nonossifying fibroma, aneurysmal bone cyst, osteoblastoma, and brown tumor.  No evidence of metastatic malignancy is identified.  The final diagnosis requires correlation with the clinical history and radiologic findings.

Cell block is unhelpful.  A cell block from the alcohol fixed smear does show some material and osteoid but there isn't sufficient architecture to allow a positive diagnosis of fibrous dysplasia which appears to be the most likely final diagnosis.

IMMEDIATE EVALUATION: LEft rib, fine needle aspiration:  No tumor identified.

GROSS DESCRIPTION:
CT-guided biopsy of left rib.  Two fixed slide, one air-dried slide, and material for cell block collected.