Clinicopathological and Radiological Correlation in Osteosarcoma: A Prospective Study of 91 Cases

ABSTRACT

Background:

Osteosarcoma is the most common primary malignant bone tumor, primarily affecting adolescents during rapid bone growth.

Materials and Methods:

A prospective study of 91 cases of osteosarcoma diagnosed at Gujarat Cancer and Research Institute, Ahmedabad (2014–2016). Clinical history, radiological imaging (X-ray, CT, MRI), and histopathological findings (H&E staining) were analyzed. Correlation with radiological features such as cortical breach, periosteal reaction, and soft tissue extension was evaluated.

Results:

Peak incidence: Second decade (60.4%), with a male-to-female ratio of 1.6:1. Common sites: Distal femur (39.6%), proximal tibia (30.7%), and proximal humerus (9.9%). Histopathological subtypes: Osteoblastic (44%), chondroblastic (22%), fibroblastic (11%), MFH-type (8.8%), giant cell-rich (4.4%), telangiectatic (4.4%), parosteal (3.3%), and small cell (2.1%). Radiological accuracy: Parosteal (100%) and small cell (100%) had the highest radiological correlation, while giant cell-rich osteosarcoma (25%) was frequently misdiagnosed. Cortical breach and periosteal reaction were observed in 92.6% of cases.

Conclusion:

Osteosarcoma predominantly affects adolescents, with metaphyseal long bone involvement. Radiology aids in primary diagnosis but lacks subtype specificity. Histopathology remains the gold standard, necessitating a multidisciplinary approach for precise diagnosis and management.

INTRODUCTION

Osteosarcoma is the most common primary malignant bone tumor, characterized by the direct formation of osteoid or bone by malignant mesenchymal cells. It primarily affects children and adolescents, with a peak incidence during periods of rapid bone growth.[1] Although primary bone tumors are relatively uncommon, osteosarcoma constitutes a significant proportion of malignant bone neoplasms, accounting for approximately 20% of all bone malignancies.[2] Most osteosarcomas arise de novo, while some develop within pre-existing conditions such as Paget’s disease, fibrous dysplasia, chronic osteomyelitis, and prior radiation exposure.[3,4]

Histopathological evaluation plays a crucial role in the diagnosis and classification of osteosarcoma. The presence of malignant osteoid production is a defining feature and differentiates osteosarcoma from other bone sarcomas.[5] Various subtypes of osteosarcoma exist, including conventional intramedullary osteosarcoma, surface osteosarcoma (periosteal and parosteal), and secondary osteosarcoma, which arises from underlying bone pathologies.[6] Prognosis largely depends on tumor grade, metastasis at diagnosis, and response to chemotherapy.[7]

Advancements in molecular genetics have identified key mutations involved in osteosarcoma pathogenesis. The RB1 and TP53 tumor suppressor genes play a pivotal role in osteosarcoma development, along with dysregulation of cyclins and cyclin-dependent kinases.[8]

MATERIALS AND METHODS

Study design and duration

This prospective study was conducted on 91 cases of osteosarcoma diagnosed at our institution between September 2014 and October 2016, aiming to correlate histopathological, clinical, and radiological findings for improved diagnostic accuracy. Patients of all age groups with a confirmed osteosarcoma diagnosis were included, provided they had adequate biopsy samples and corresponding radiological data (X-ray, CT scan, MRI). Cases lacking sufficient biopsy material or radiological information were excluded. Clinical history, including tumor site, presenting symptoms, and functional limitations, was obtained from medical records.

Radiological assessments were conducted using X-rays, CT scans, and MRI, evaluating tumor location, lesion type, cortical integrity, periosteal reactions (Codman’s triangle, sunburst pattern, onion-skin appearance), and soft tissue extension. Histopathological evaluation involved formalin-fixed, paraffin-embedded tissue sections stained with hematoxylin and eosin (H&E). Microscopic examination assessed tumor cell morphology (anaplastic, pleomorphic, fusiform, ovoid, small round cells), osteoid formation, matrix differentiation (osteoblastic, chondroblastic, or fibroblastic), mitotic activity, necrosis, and hemorrhage.

A definitive diagnosis was made by integrating histopathological, radiological, and clinical findings. The classification of osteosarcoma subtypes was based on histomorphological patterns and matrix composition. Radiology played a crucial role in identifying osteosarcoma but lacked specificity in subtyping. Histopathological examination [Figure 1] remained the gold standard for tumor classification, reinforcing the need for a multidisciplinary approach to osteosarcoma diagnosis and management.

Figure 1.

Giant cell rich Osteosarcoma Telangiectatic Osteosarcoma Parosteal Osteosarcoma

RESULTS

This study analyzed 91 cases of osteosarcoma, categorizing them into different histopathological subtypes. The osteoblastic subtype was the most prevalent (44%), followed by chondroblastic (22%) and fibroblastic (11%) variants. Less common subtypes included MFH-type (8.8%), giant cell-rich (4.4%), telangiectatic (4.4%),[9] parosteal (3.3%), and small cell osteosarcoma (2.1%) [Table 1]. The second decade of life was the most affected age group (60.4%), with a male-to-female ratio of 1.8:1, indicating a slight male predominance. The most commonly involved site was the distal femur (39.6%), followed by the proximal tibia (30.7%) and proximal humerus (9.9%). Histopathological examination revealed that osteoid production by malignant cells was the key diagnostic criterion, with tumor differentiation varying by subtype. Osteoblastic osteosarcoma presented with dense neoplastic bone matrix, while chondroblastic osteosarcoma displayed hyaline cartilage with focal osteoid, and fibroblastic osteosarcoma showed spindle cells arranged in intersecting fascicles.

Table 1.

Histopathological diagnosis and distribution

Diagnosis	No of Patients	Percentage
Osteoblastic	40	44%
Chondroblastic	20	22%
Fibroblastic	10	11%
MFH type	8	8.8%
Giant cell-rich	4	4.4%
Telangiectatic	4	4.4%
Parosteal	3	3.3%
Small cell type	2	2.1%

Radiological evaluation was crucial in identifying osteosarcoma, with cortical breach and periosteal reaction observed in 92.6% of cases and soft tissue extension in 87.7%. The highest radiological correlation was observed in parosteal[10] and small cell osteosarcoma (100%), followed by osteoblastic (90%), fibroblastic (90%), and chondroblastic (80%) subtypes. In contrast, giant cell-rich osteosarcoma had the lowest radiological correlation (25%), often misdiagnosed as a giant cell tumor or chondroid malignancy [Table 2]. Telangiectatic osteosarcoma was frequently mistaken for aneurysmal bone cyst, but CT and MRI helped differentiate it based on nodular tissue and matrix mineralization. Clinical presentation was similar across subtypes, with pain and swelling as the most common symptoms, while telangiectatic osteosarcoma had a higher incidence of pathological fractures. These findings highlight the importance of combining histopathology, radiology, and clinical evaluation for accurate osteosarcoma diagnosis and classification.

Table 2.

Correlation between histopathological and radiological diagnosis

Histopathological Diagnosis	Correct Radiological Diagnosis	Percentage
Osteoblastic	36/40	90%
Chondroblastic	16/20	80%
Fibroblastic	9/10	90%
MFH type	7/8	87.5%
Giant cell-rich	1/4	25%
Telangiectatic	3/4	75%
Parosteal	3/3	100%
Small cell type	2/2	100%

DISCUSSION

Osteosarcoma is the most common primary malignant bone tumor, predominantly affecting adolescents, with a peak incidence in the second decade of life (60.4%).[1,2] Males were more frequently affected (M: F ratio = 1.6:1), aligning with previous studies.[3,4]

The metaphysis of long bones was the most commonly involved site, particularly the distal femur (39.6%), followed by the proximal tibia (30.7%) and proximal humerus (9.9%).[5]

Histopathologically, osteoblastic osteosarcoma was the most common subtype (44%), followed by chondroblastic (22%) and fibroblastic (11%) variants, similar to prior reports.[4,6] However, biopsy sampling bias may account for variations in subtype prevalence.[7] Radiology played a crucial role in primary diagnosis (89% accuracy) but was insufficient for precise subtyping, as lytic lesions in chondroblastic and fibroblastic osteosarcoma were difficult to distinguish.[8] Parosteal osteosarcoma was the most accurately diagnosed radiologically (100%), while giant cell-rich osteosarcoma had the lowest radiological correlation (25%)[11] due to its resemblance to giant cell tumors or chondroid malignancies.[6]

This study confirms that radiological evaluation is essential for tumor detection and assessing extent, but histopathological examination remains the gold standard for classification and grading.[7,8] A multidisciplinary approach integrating clinical, radiological, and histopathological findings is essential for accurate diagnosis and optimal management of osteosarcoma.

CONCLUSION

The study confirms that histopathology remains the gold standard for definitive diagnosis, subtyping, and grading of osteosarcoma. Despite advances in imaging, accurate diagnosis requires a multidisciplinary approach, integrating clinical, radiological, and histopathological data. Given the aggressive nature of osteosarcoma, early and precise diagnosis is crucial for optimal treatment and improved patient outcomes. Thus, a combined approach involving histopathological evaluation, radiological assessment, and clinical correlation is essential for accurate diagnosis and effective management of osteosarcoma.

Conflicts of interest

There are no conflicts of interest.

Funding Statement

Nil.