Contributed by Kate Serdy, MD and Alka Palekar, MD
An 80 year old man presented with right-sided hip pain and a palpable groin mass. Imaging showed a right acetabular fracture associated with a radiolucent soft tissue mass (Fig. 1). FNA of the mass was consistent with chondrosarcoma. Total hemipelvectomy was performed and the surgical specimen was received in five parts.
Specimen received shows a diffuse lesion involving the femoral head and neck, pubic bone, ilium and ischial portion of pelvic bone and soft tissue. In the bone, the lesion appears yellow-red, ill-defined, and expansile associated with foci of frank necrosis (Figs. 2A and 2B). The soft tissue contains multiple nodules which have a tan-grey color on cut surface and a gelatinous, almost friable quality (Fig 2C).
Microscopic evaluation of bone and soft tissue tumor reveals two distinct morphologies. They are sharply demarcated without a transition zone (Fig. 3E). The first morphological pattern is arranged as irregular lobules of chondromyxoid matrix. Within the lobules, small, mildly pleomorphic cells are identified within lacunae and have enlarged nuclei with an open chromatin pattern. This neoplasm permeates through bone (Fig. 3A). The second morphological pattern is characterized by pleomorphic cells haphazardly arranged in sheets and cords, associated with extensive necrosis (Figs. 3B, 3C). The cells have enlarged nuclei with prominent nucleoli. Mitoses are readily identifiable and include some atypical forms. This component extends through bone into adjacent soft tissue. Focal osteoid production is seen, which is confirmed with osteocalcin immunohistochemical staining (Fig. 3D). Lymphovascular invasion is identified (Fig. 3F).