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Study of Bone Tumors in a Tertiary Care Hospital of Dhaka City

Background: The wide spectrum of bone tumors, their rarity, diverse origin and tendency to produce overlapping anatomic patterns pose a definite diagnostic challenge to the orthopedic surgeons and the pathologists. Objective: The present study was intended to find the pattern of bone tumors and their anatomical locations, and histopathological characteristics in a tertiary care hospital of Dhaka. Methodology: A retrospective review of the histopathological records of patients with established diagnosis of bone tumors at National Institute of Traumatology and Orthopedic Rehabilitation (NITOR), Dhaka, Bangladesh was done from January 2015 to December 2016 for a period of two (02) years. The demographic data such as the age and sex, anatomical location and histopathological findings were studied from the existing records of the patients and their slides were reexamined. Bone lesions of inflammatory origin were excluded from this study leaving the lesions of both neoplastic and tumor-like origin for further study. Result: A total 283 cases of bone lesions were primarily included in the study. Bone lesions of inflammatory origin (n = 65) were excluded from this study leaving 218 lesions of both neoplastic and tumor-like origin for further study. The median age of the patients was 22 (range: 3 – 75) years. In terms of anatomical site of the tumors, over one-third (36.6%) was located in femur 21.1% in tibia, 12.2% in humerus, 6.1% in radius and 5.6% in ulna. In terms of types of bone tumor, 105(48.2%) were benign, 66(30.3%) malignant, 47(21.5%) tumor-like lesions. About 65% of the benign tumors were of Giant cell tumor, 28.5% were osteochondroma, 1% osteoma and 5.7% were of other types. Of the malignant tumors, one-third (33.3%) was of metastatic type, 27.3% Ewing’s sarcoma, 22.7% osteosarcoma, 9.1% chondrosarcoma and 4.6% were of other varieties. Conclusion: Primary bone tumors are mainly benign; however, giant cell and metastatic tumors are the most common benign and malignant bone tumors respectively. [Journal of Current and Advance Medical Research 2018;5(1):23-28]


Introduction
Bone tumors are infrequently encountered diseases constituting only 0.5% of the total world cancer incidence compared to the occurrence of other neoplastic lesions 1 . However, they are of great significance because majority of them affect adolescents and young adults with a tendency of aggressive course 2 .Besides, the wide spectrum of these tumors, their diverse origin from the multiple cell types found in bones coupled with their tendency to produce overlapping anatomic patterns make them a complicated but highly challenging area from the point of view of morphological diagnosis 3 .
Primary bone cancer is much rarer than bone metastasis. Bone is the third most common site of metastatic disease. As far as secondary tumors are concerned primary sites like lung, kidney, thyroid, breast, gastrointestinal and melanomas produce mainly lytic lesion while others elicit mixed lytic and sclerotic reaction.
Carcinomas are much more likely to metastasize to bone than sarcomas 4,5 . The wide spectrum of bone tumors, their diverse origin and tendency to produce overlapping anatomic patterns present a daunting challenge to the orthopedic surgeons and the pathologists.
The challenge is heightened in developing countries due to limited diagnostic and therapeutic facilities as well as due to ignorance. The published literature on the subject is sparse in our context. As already mentioned, bone cancer is not a common malignant disease, and perhaps for this reason its etiology is not very clear. Furthermore, very few studies have been conducted in this field. Among different types of primary bone cancer, osteosarcoma constitutes the highest proportion (36%) of cases, followed by chondrosarcoma, osteoclastoma and Ewing's sarcoma 6 .
The clinicians and the pathologists handling management responsibility, therefore, must have high index of suspicion as to the nature of bone lesion in order to establish the diagnosis of bone tumors.
The purpose of the present study is to determine the pattern of bone tumors including their relative frequencies, age and sex distributions, anatomical locations, and histopathological characteristics as seen in a tertiary care hospital of Dhaka.

Methodology
This retrospective review of the histopathological records of patients with established diagnosis of bone tumors at National Institute of Traumatology and Orthopedic Rehabilitation (NITOR), Dhaka, Bangladesh was done covering the period from January 2015 to December 2016 for a period of two (02) years. The demographic data such as the age and sex, anatomical site and histopathological findings were extracted from the existing records of the patients and their hematoxylin and eosin (H and E)-stained slides were all reexamined. Chronic inflammatory lesions of bone were excluded from this study leaving 218 lesions of neoplastic and tumor-like origin for further study. Among the bone lesions, some were primary bone tumors, some were metastatic tumors and some were tumor-like lesions. The classification was based on the current World Health Organization (WHO) histological classification of bone tumors 7 . Data were analyzed using SPSS (Statistical Package for Social Sciences), version 17.0 with test statistics being used were frequency distribution with corresponding percentages and median with standard deviation and range.

Result
A total 283 cases of bone lesions were primarily included in the study. Bone lesions of inflammatory origin (n = 65) were excluded from this study leaving 218 lesions of both neoplastic and tumorlike origin for further study. In terms of anatomical site of the tumors, over onethird (36.6%) was located in femur 21.1% in tibia, 12.2% in humerus, 6.1% in radius and 5.6% in ulna. Fibula and pelvis each comprised 3.8% of the lesions ( Table 2).  (Table 3).

Discussion
In the present study out of 283 patients of bone lesions provisionally included in the study, 218(77%) were neoplastic bone lesions and 65(23%) were of infectious or inflammatory origin (mostly of chronic non-specific inflammation). As per enrolment criteria of the present study, the latter were excluded leaving 218 for further study. Of the neoplastic lesions, nearly half (48.2%) was benign in nature, 30.3% malignant and 21.5% tumor-like lesions. Rhutso and colleagues 8 in a study also demonstrated an almost similar distribution of neoplastic (63.3%) and non-neoplastic lesions (36.7%). Sharply contrasting with these findings, Modi et al 9 showed that the incidence of nonneoplastic lesions was 74.5% and neoplastic lesions were 25.4%. The non-neoplastic lesions were predominantly chronic osteomyelitis. A significant proportion of neoplastic bone lesions (35.8%) in this study was seen to occur in children and adolescents (age ranging from 10 to 20 years) which compares well with the findings of Sunila et al 6 (33.3%). Several other studies 1,10-11 also reported similar findings.
Anatomical location of the bone tumors showed that long bones are the preferred site of bone tumors, for 70% of lesions were found in the three bones like femur, tibia and humerus which is consistent with the findings of Sunila et al 6 . The most common bones involved were the long bones; less commonly the jaws, vertebrae, scapula pelvis, and small bones of hands and feet were involved [12][13][14][15] .Another important finding is that benign tumors were predominantly of Giant cell type, while metastatic tumors were common (33.3%) among malignant lesions followed by Ewing's sarcoma and osteosarcoma which differs from the findings of the several other investigators 1,6,9,16 who reported osteochondroma to be the most common benign bone tumors accounting for 20 to 40% of all the benign tumors, while osteosarcoma to be the most common primary bone tumors in young and adolescents. It occurs most frequently in the second decade, occurring in the metaphysis, mostly in lower end of femur followed by upper end of tibia [13][14][15]17 . Ewing sarcoma is a highly malignant, undifferentiated, peripheral primitive neuroectodermal tumor occurring most commonly at the diaphysis of long bones, in the 0 to 20 years age group, with male predominance [13][14][15] .
Chondrosarcoma is the most common primary malignant bone tumor in the age group of 40 to 60 years, which in our study comprised 9.0% of the malignant tumors. It commonly involves pelvis, femur, ribs, shoulder girdle, and vertebra with male predilection [13][14][15] .
Metastatic bone tumors most frequently occur in patients older than 50 years and commonly originate from lung, gastrointestinal system, prostate, breast, and liver. Femur, pelvis, vertebrae, humerus, and rib are the most common sites of metastases [13][14][15]17 . The clinical manifestation is extensive and nonspecific. Most lesions present with osteolytic patterns 18 . In spite of complexity, the clinical features should be mastered for early diagnosis and treatment.

Conclusion
From the findings of the study it appears that primary bone tumors are mainly benign, occur predominantly in the second decade of life with a male preponderance and predilection for long bones. Giant cell tumor and metastatic tumors are the most common benign and malignant bone tumors respectively, while Ewing's sarcoma is the common primary malignant lesions in the context of our population.