Telangiectatic osteosarcoma: Pathological rarity and scintigraphic exclusivity.

Sir,

We take this opportunity to report a rare case of telangiectatic osteosarcoma highlighting the exclusive scintigraphic features.

A female aged 13 years presented with throbbing pain of one-year duration in the left upper arm with a gradually progressing swelling. The swelling was growing rapidly since three months and was not associated with any constitutional symptoms. There was no history of any trauma and no other similar swellings were noted in the rest of the body.

Plain radiograph of the left shoulder joint including the entire shaft revealed osteolytic lesions in the diametaphyseal region of left humerus with a wide zone of transition between the lesion and the adjoining bone. There was periosteal elevation with a soft tissue component and no calcification seen in the matrix or the soft tissue. Radiological features were consistent with osteosarcoma [Figure 1] and the case was referred for skeletal scintigraphy to rule out any metastasis.

Figure 1

X-ray of left shoulder including the entire shaft of humerus showing osteolytic lesions in the diametaphyseal region of left humerus with a wide zone of transition between the lesion and adjoining bone. There is periosteal elevation with a soft tissue component

Technetium-99m (99mTc)-methylene diphosphonate (MDP) skeletal scintigraphy revealed a large irregular-shaped intensely avid uptake with speculated margins seen in the upper one-third of the left humerus. The uptake predominantly involved the soft tissues around the humerus. No metastatic foci were seen in the rest of the skeleton. No foci of uptake were seen in the lung [Figure 2]. Fine needle aspiration cytology from the swelling revealed features of the telangiectatic variety of osteosarcoma. Disarticulation of the left upper limb was done. Pathological gross specimen showed a tan-white tumor filling most of the medullary cavity of the metaphysis and proximal diaphysis of the left humerus with a large soft tissue component [Figure 3]. Histopathology revealed bony trabeculae with the lesion infiltrating between them. The lesion was composed of multiple cystic spaces separated by thin cellular septa and filled with blood. The surrounding soft tissues showed infiltration of tumor but skin and subcutaneous tissues were free. Histopathological features were consistent with ‘telangiectatic osteosarcoma’ arising from the proximal part of the humerus [Figure 4]. Enneking clinical and histological staging was stage II B - G3-T2-N0-M0.

Figure 2

Technetium-99m ([99m]Tc)- methylene diphosphonate (MDP) skeletal scintigraphy showing intensely avid uptake in the proximal end of left humerus and adjoining soft tissue. Soft tissue component is more than bony component

Figure 3

Gross specimen showing a tan-white tumor at the metaphysis and proximal diaphysis of left humerus with large soft tissue component

Figure 4

Histopathology showing bony trabeculae with the lesion infiltrating between them; the lesion composed of multiple cystic spaces separated by thin cellular septa and filled with blood. The surrounding soft tissues showed infiltration of tumor

Osteosarcoma is an ancient and serious form of musculoskeletal cancer and most patients die from pulmonary metastatic disease, and thus are usually referred for metastatic workup to assist in diagnostic staging.[12] Major sites are lower ends of femur and upper end of tibia, hemipelvis, proximal end of femur, humerus, and mandible. It is a malignant mesenchymal tumor in which cancer cells produce bone matrix and is the most common primary malignant tumor of bone accounting for approximately 20% of them. Most arise from the metaphysis of the long bones. Radiological features include osteolytic lesions, osteoid matrix, and periosteal elevation with the classical ‘Codman Triangle’.[3] Osteosarcomas are named after their location and type of matrix such as osteoid, chondroid and fibrous type matrix, periosteal, parosteal and telangiectaic . The telangiectatic variety is an unusual variant characterized by a preponderance of vascular channels amidst osteoid-staining malignant cells; it is a highly aggressive variant of osteosarcoma.[4] Despite lack of any specific features of scintigraphic uptake in osteosarcomas, large irregular-shaped uptake with extension far beyond the confines of the humerus shaft, and the preponderance of the soft tissue component far exceeding the bony component and the speculated and irregular outlines of the tumor uptake favored the possibility of a soft tissue predominating type of osteosarcoma, the telangiectatic osteosarcoma,[5] which was confirmed on histopathology.