Cytological diagnosis of skeletal lesions. Fine-needle aspiration biopsy in 110 tumours.

We have previously shown that cytological diagnosis based on fine-needle aspiration biopsy (FNAB) is a safe and efficient method for the discrimination between benign, primary malignant and metastatic bony lesions. We have now studied metastatic lesions to assess the diagnostic accuracy and to ascertain whether FNAB allows identification of the primary lesion. Between 1990 and 1997, 447 patients were referred for diagnosis of skeletal lesions of unknown type. Of these 119 proved to have metastatic disease, either myeloma or lymphoma. Nine were excluded leaving 110 consecutive patients with metastatic carcinoma (80), myeloma (16) or lymphoma (14). FNAB gave a correct diagnosis in 102 of the 110 patients (93%). In eight it was inconclusive. It correctly diagnosed 15 of 16 patients with myeloma, 12 of 14 with lymphoma, and 75 of 80 with metastatic carcinoma. Furthermore, the site and type of malignancy were correctly suggested in two-thirds of patients with metastatic carcinoma. Overall, only seven open biopsies were carried out. We conclude that time-consuming and costly investigations can be reduced by choosing FNAB as the initial diagnostic method for skeletal lesions of unknown origin. The choice of radiological examinations, laboratory tests and surgical biopsies can be determined by using FNAB.