Fine-needle aspiration biopsy of skeletal versus extraskeletal osteosarcoma

Although fine-needle aspiration biopsy (FNAB) of primary skeletal osteosarcoma (OS) has been described adequately, to the authors' knowledge, cytologic descriptions of extraskeletal OS appear limited to only rare case reports.

In an attempt to analyze the utility and accuracy of FNAB in a diagnosis of skeletal versus extraskeletal OS, the authors retrospectively reviewed their 5-year experience. The study sample included 15 skeletal OS specimens (13 primary, 1 local recurrence, and 1 pulmonary metastasis) in 14 patients ages 10-58 years (mean, 27 years; median, 25 years) and 5 extraskeletal OS specimens (3 primary and 2 metastatic) in 4 patients ages 36, 37, 65, and 79 years, respectively. Based on accepted clinical criteria, two patients (a mother with extraskeletal OS and a daughter with skeletal OS) had Li-Fraumeni syndrome.

Of the adequate primary skeletal OS cases analyzed by FNAB, 10 of 12 (83%) were diagnosed correctly and subsequently treated according to a disease specific protocol. One case was considered unsatisfactory. One tumor initially was diagnosed as a giant cell tumor and another was referred to nonspecifically as "spindle-cell neoplasm." On histologic examination, the former case demonstrated a high grade fibroblastic OS arising within a giant cell tumor. None of the primary extraskeletal OS cases analyzed by FNAB was recognized as OS. One was diagnosed nonspecifically as "sarcoma" and the other was referred to simply as "atypical mesenchymal cells." A third case was comprised of scant fragments of adipose tissue, fibrous tissue, and cartilage and was considered unsatisfactory. Both examples of metastatic extraskeletal OS were recognized by FNAB.

With appropriate clinicoradiologic correlation, skeletal OS generally is easily diagnosed by FNAB. Because of the older age of most patients with extraskeletal OS and the rather nonspecific radiographic findings (e.g., soft tissue mass), extraskeletal OS may not be recognized easily by FNAB and most likely requires incisional biopsy to establish a definitive diagnosis in most cases. Additional larger series will be required before drawing definite conclusions.