Should fine needle aspiration biopsy be the first pathological investigation in the diagnosis of a bone lesion? An algorithmic approach with review of literature

Fine needle aspiration biopsy (FNAB) is gaining increasing popularity in the diagnosis of musculoskeletal lesions; and in many patients, a definitive diagnosis can be rendered from aspiration smears alone. Its applicability in bone pathology, however, has been controversial due to a high percentage of inadequate smears, difficulty in evaluation of tissue architecture and nonspecific results in the diagnosis of primary bone lesions. In this study, the value of aspiration as the first pathological investigation in the diagnosis of a bone lesion was evaluated. 91 cases of clinically suspected cases of bone lesions were aspirated over a period of two years. Direct or cytospin smears were fixed in 95% alcohol and stained by Hematoxylin and Eosin or air-dried and later fixed in methanol for May Grŭnwald Giemsa staining. Of the 91 patients who were subjected to FNAB, 81 were considered satisfactory and 10.9 % (10) were inadequate\inconclusive for diagnosis. Cyto-histological concordance was obtained in 78.5 % (51/65) patients. Positive and negative predictive values were 87.5% and 97.2 % respectively. Sensitivity as a preliminary diagnostic technique was 93.3%, whereas specificity was 94.5 %. Overall, diagnostic accuracy was 94.2 %. Metastatic lesions were detected with 100% accuracy. Two cases were reported as false positive and one case as false negative. Cytology provides valuable information to the clinician to make an informed decision regarding appropriate therapy. We conclude that time-consuming and costly investigations may be reduced by choosing FNAB as the initial pathological diagnostic method for skeletal lesions of unknown origin. The choice of radiological examinations, laboratory tests and surgical biopsies can be determined after the FNAB diagnosis.