Anatomic Pathology / FNAB Cytomorphology in Chondromyxoid Fibroma

We describe the cytologic features of chondromyxoid fibroma in fine-needle aspiration biopsy specimens in 4 patients. We analyzed rapid Romanowsky– and Papanicolaou-stained slides with a respect to overall cellularity, the presence of hypercellular chondromyxoid fragments (HCFs), nuclear atypia, cytoplasmic features, and the presence of giant cells. The most consistent and diagnostically useful feature was the presence of HCFs, which were present in all 4 cases. Mild to moderate nuclear atypia was additionally present in all 4 cases. Most cases were hypocellular (3/4). Giant cells were present in 2 cases, with 1 case exhibiting a hypercellular smear with numerous giant cells. All 4 cases were confirmed in subsequent histologic biopsy material. Strict attention to clinical, radiographic, and cytologic features, especially the presence of HCFs, can aid in the specific diagnosis of chondromyxoid fibroma on FNAB. Chondromyxoid fibroma (CMF) is a benign neoplasm accounting for fewer than 1% of all bone tumors. It has a predilection for men in the second and third decades of life with the metaphyseal regions of the long bones of the lower extremities as the favored sites of occurrence. Other sites include the small bones of the feet and the ilium.1-5 Radiographically, CMF manifests as an eccentrically situated, well-circumscribed, oval metaphyseal lesion parallel to the long axis of the bone. Relatively few cases have been reported in fine-needle aspiration biopsy (FNAB) specimens.6-11 This study presents 4 cases of CMF in FNAB. The cytologic findings and usefulness of FNAB in the diagnosis of CMF are emphasized. Materials and Methods Rapid Romanowsky– and Papanicolaou-stained smears from 4 cases of CMF on FNAB specimens were selected from a review of our files. The cases were analyzed with respect to overall cellularity, presence of hypercellular chondromyxoid fragments (HCFs), nuclear atypia, cytoplasmic features, and the presence of giant cells. We define HCFs as small chondromyxoidal mesenchymal masses in which variable numbers of benign-appearing, elongated, and stellate contoured stromal cells are present. In addition, clinical and radiographic features were reviewed.