Histopathology:
The Hematoxylin and eosin stained sections revealed superficial
stratified squamous epithelium and underlying connective tissue. The
lesion appeared to be well encapsulated(Figure 8E). Focal areas of
connective tissue stroma was myxomatous (Figure 8C), collagenous and
hyalinized. Areas of spindle and stellate shaped fibroblastic cells
(Figure 8D) and atypical, hyperchromatic, fusiform chondroblastic cells
proliferation (Figure 8A), bizarrely shaped mitotic figures along with
adjacent malignant osteoid tissue was evident (Figure 8B). Osteoid was
scanty and immature. Chondroblastic proliferation was dominant and
aggressively proliferating with areas showing pleomorphism. Hence,
histopathological diagnosis of chondroblastic osteosarcoma was made.
Discussion: Osteosarcomas are difficult to diagnose even with
immunohistochemistry and advanced radiography as single lesion may show
osteoid in one region along with scattered chondroid, myxoid, fibrous
areas. Superficial layers may show benign fibrous growth with epithelial
hyperplasia which is the most common site of biopsy. Such diversity of
histopathology in various areas of lesion pose a challenge to surgeon to
procure representative biopsy specimen. When suspecting a
osteosarcomatous lesion surgeon should prefer deeper hard tissue
biopsies preferably the hard tissue growing beyond the confines of
cortices. These sites are more representative of actual pathology rather
than superficial fungating tumour mass which is comparatively easier to
excise.
In this case final histopathology of excised hard tissue specimen was
confirmative of very rare mixed form of chondrogenic osteosarcoma. The
role of neo-adjuvant chemotherapy in chondroblastic osteosarcoma is
limited to tumour mass shrinkage and to achieve negative tumour
margins7. But due to its rapid metastasis, before
definitive surgery patient was advised neo-adjuvant chemotherapy with
doxorubicin 80 mg and cisplatin 140 mg, but even after 2 cycles there
was no considerable decrease in size of tumour mass which was in
accordance with chemoresistance mechanisms in osteosarcoma. Altered
deoxyribonucleic acid (DNA) repair activity8,
overexpression of resistance-related proteins such as metallothioneins,
glutathione-S-transferase π, heat shock protein 27, and lung
resistance-related protein9 and alterations in cell
cycle10 are the probable factors for chemoresistance.
As definitive surgery patient underwent right side supra-omohyoid neck
dissection and right hemi-mandibulectomy(Figure 9) followed by
reconstruction with anterolateral thigh flap(Figure 10,11) in Department
of Surgical Oncology. Following which patient was referred to
radiotherapy.
Low and intermediate grade osteosarcomas are juxtacortical, medullary or
periosteal in nature. Whereas aggressive high grade osteosarcomas are
classified by World Health Organization (WHO) in 4 histopathological
types as per predominance of tissue found. Osteoblastic, chondroblastic,
fibroblastic and small cell types as the name suggests show predominance
of respective tissue. Yet another telangiectatic form is also described
in the literature11.