Potential Seeding From Fine-Needle Aspiration of an Axial Osteosarcoma: A Case Report

Abstract

This report describes the first potential case of seeding after fine-needle aspiration (FNA) of a rib osteosarcoma in a dog. An 8-year-old, 28-kg female spayed Golden Retriever was presented to her primary veterinarian with a 3-week history of a 3-cm firm, unpainful, immobile mass arising from the 9th rib. The mass was aspirated and submitted for cytological examination. A subcutaneous nodule developed several days after the FNA was performed in a location immediately overlying but distinct from the primary rib tumor on palpation. Both the primary mass and the newly diagnosed subcutaneous nodule were biopsied and were consistent with an osteosarcoma. Although it cannot be ruled out that the subcutaneous lesion was metastatic, seeding was a reasonable explanation based on where the new mass was located and how quickly it appeared after the FNA was performed. The aim of this case report was to describe the possibility of tumor seeding during FNA for osteosarcoma. It is the authors' opinion that utility of cytological diagnosis of bone tumors outweighs the risk of possible seeding and should continue to be used as a routine diagnostic test for the diagnosis of aggressive bone lesions.

Telangiectatic osteosarcoma in four dogs: Cytologic, histopathologic, cytochemical, and immunohistochemical findings

“…For these patients, distinguishing between bone HSA and tOSA may substantially influence the treatment plan, from radiation therapy planning to adjuvant chemotherapy recommendations and potential immunotherapy. Subcutaneous seeding from the fine‐needle aspiration of an axial osteosarcoma was reported in a dog, but this appears rare 13 …”

“…Subcutaneous seeding from the fine-needle aspiration of an axial osteosarcoma was reported in a dog, but this appears rare. 13 We describe the cytologic features of tOSA, which include a pleomorphic population of atypical mesenchymal cells with evidence of hemorrhage and positive cytochemical staining for ALP. A complete clinical picture, including imaging, cytology, and special staining, can help distinguish tOSA from other neoplasms, such as HSA, that present with similar pathologic characteristics; histopathology will still be needed for final diagnosis.…”