Spectrum of Hematological and Non-Hematological Diseases on Bone Marrow Examination-A Study on 220 Cases at a Tertiary Care Centre

Background: Bone marrow examination is an invaluable tool in the diagnosis of hematological and nonhematological diseases. Referral is made based on the clinical evaluation followed by after analysis of CBC and


Introduction
Bone marrow examination is a detailed procedure for analyzing the pathologies of bone marrow samples obtained through bone marrow aspiration and biopsy (often termed as trephine biopsy). Bone marrow aspiration is utilized for obtaining specimens for cytological evaluation, with analysis being directed toward the assessment of morphology and for obtaining a differential cell count. It further allows the samples to be directed towards other specialized tests, such as cytogenetics, molecular studies, microbiologic cultures, immunohistochemistry, and flow cytometry. 1,2 Bone marrow aspiration and biopsy is the most frequent and safe invasive procedure carried out in hospitals for the diagnosis of hematological and non-hematological diseases. 3,4 The hematological diseases include acute leukemia, myeloproliferative disease (MPD), lymphoid neoplasm and various nutritional deficiency diseases whereas nonhematological diseases include infectious diseases infiltrating the bone marrow such as tuberculosis, parasitic infections, metastatic deposits and metabolic storage diseases. 5 Although a peripheral blood smear is carried out in patients with suspicion of hematological diseases, it alone does not reflect on the nature of disease process. Thus, a bone marrow biopsy is indicated based on the suspicion from clinical picture and peripheral blood smear. 6 This study aims at evaluation the spectrum of diseases diagnosed on bone marrow biopsy at a tertiary care hospital of Rawalpindi, Pakistan. There is a wide spectrum of diseases revealing bone marrow changes. Majority of these disorders present with vague clinical symptoms and poses difficulty for clinicians in the diagnosis based on complete blood picture and peripheral film only; necessitating the use of bone marrow aspiration and examination for diagnosis. 7 Rationale of the study is to ascertain the etiological spectrum of disorders on bone marrow examination which will guide the clinicians about the frequency of hematological and non-hematological disorders and their management in a clinical setup.

Materials and Methods
A descriptive cross-sectional study was conducted at the pathology department of Holy Family Hospital. All 220 cases requiring bone marrow examination for various hematological disorders were included in the study, from March 2016 to March 2017. Patients having contraindications for bone marrow aspirations such as skin infection at site of sample, osteomyelitis, active bleeding were excluded from study. Ethical approval was taken from the ethical review board before proceeding with data collection. The bone marrow examination was carried out in the group of patients who were referred to the pathology department because of unexplained anemia, pancytopenia, hematological malignancies, leukemia or thrombocytopenia. A detailed history, examination and all the relevant investigations were done. Peripheral blood smears, complete blood count and hematological parameters were performed prior to bone marrow aspiration. A written consent was taken from the patients by the concerned department. Bone marrow was collected by bone marrow aspiration needle under aseptic conditions after giving local anesthesia. An aspirate smear was prepared and stained. The slide was observed under the microscope and the findings were noted. Data were entered and analyzed using SPSS v22. Mean and standard deviation were calculated for quantitative variables. Frequencies and percentages were calculated for qualitative variables, such as for diagnosis and gender. A chi-square test of independence was applied to find out the association between indications of referral and diagnosis of bone marrow examination. The p-value to be considered statistically significant for the test was set at ≤ 0.05. A post-hoc comparison was further carried out between indications and hematological diseases with p-value being ≤ .0004 by Bonferroni correction.
The blood cell counts were highly variable (Table-I).
On peripheral blood film examination, 24 had a normocytic normochromic picture, 38 had a microcytic hypochromic picture, 18 were macrocytic, and 140 had a dimorphic picture. The most frequent indications for which the patients were referred for bone marrow examination were pancytopenia in 113(51.3%), hematological malignancy in 53(24%) and anemia in 32(14.5%) cases (see Figure-1). 86% of the specimens showed hypercellularity of bone marrow. The spectrum of hematological and non-hematological diseases as found on bone marrow examination ranged from acute leukemia in 37(16.8%), megaloblastic anemia in 29(13.1%) to some very rare diseases as Diamond Blackfan syndrome and Bernard-Soulier syndrome in 1 specimen each (see Table-II). Among the 10 cases of patients suffering from anemia of chronic disease, 4 (40%) had a past history of tuberculosis. When examining the association between indications for which referral was made and definitive diagnosis on bone marrow examination, a chi-square test of independence revealed that the relationship between these variables was statistically significant χ2(112, N=220) = 264.9, p-value < .001. A post-hoc comparison was further carried out with p-value set as ≤ .0004 by bonferroni correction. The results are shown in Table-III and Table-IV. The results show that the referral indication by the clinician based on complete blood count and peripheral blood film, was same as the final diagnosis of bone marrow examination in 29.5% cases. Moreover, pancytopenia was found to be the major indication in most diseases (32.7%), commonest being in megaloblastic anemia, followed by aplastic anemia.

Discussion
Bone marrow examination is an important tool in diagnosis of various hematological and nonhematological diseases. 8,9 This study basically aimed at determining spectrum of diseases diagnosed on bone marrow examination and finding the most common indication of referral in our setup. A total of 220 patients were included in our study with a male to female ratio of 1.13:1. Mean age was 29.15±20.9 years, compared to mean age of 38±2.33 years in another study. 10 Common clinical presentations were fever, generalized weakness, dyspnea, weight loss and bleeding manifestations. These were similar to the findings of the studies done by Prajapati et al and Belai et al. 11,12 Pancytopenia has been one of the biggest diagnostic dilemmas for clinicians and presents as the most frequent indication (51.3%) for bone marrow examination in our study. Similar to this, pancytopenia was the major indication of referral in a study done by Pudasaini et al and Ghartimagar. 3,13 However, it was in contrast to the study from Saudi Arabia 10 , in which acute leukemia was the most common indication. Bone marrow was found to be hypercellular in most cases (86%), followed by hypocellular (12%) and normocellular (2%). This was similar to the study conducted by Pudaisani et al. 3 On bone marrow examination, benign hematological diseases (62.7%) comprised of most cases, followed by malignant hematological diseases (32.7%) and nonhematological diseases (4.5%). This was similar to a study conducted by Gandapur et almand Meena, in which benign hematological diseases contributed to 73.2% of all diagnoses. 14,15 However, it was contrary to studies conducted in Saudi Arabia and India where malignant hematological diseases were the most common diagnosis (82.5%). 10,16 Among the benign hematological diseases, megaloblastic anemia was the most frequent diagnosis observed, seen in 29 cases. Similarly, megaloblastic anemia was also the commonest condition (found in 37 cases) in a study conducted in Peshawar. 17 In a study conducted in Khyber Pakhtunkhwa, hemolytic anemias were the commonest condition. 18 In another study, megaloblastic anemia was the second most common diagnosis comprising of 16.6% of the cases. 19 Among the malignant hematological diseases, the highest numbers of cases (34) were those of acute myeloid leukemia, followed by chronic myeloid leukemia. In another study, similar results were found, acute leukemia being the most prevalent hematological malignancy (34.6%) followed by chronic myeloid leukemia (28.8%). 12 Our study showed that referral indication by the clinician based on complete blood count and peripheral blood film, was same as the final diagnosis of bone marrow examination in 29.5% of the cases. This shows that these investigations alone can lead to diagnosis in many cases. However, bone marrow examination is still necessary for the confirmation of final diagnosis. Moreover, it was found out that pancytopenia was the major indication in most diseases (32.7%), commonest being in megaloblastic anemia, followed by aplastic anemia, as shown in Table-IV. Likewise, the commonest cause for pancytopenia was megaloblastic anemia (79%) followed by aplastic anemia (18%) in a study conducted by Gayathri et al. 20 Conclusion Herein, indications of bone marrow examination were pancytopenia, followed by hematological malignancies. Spectrum of diagnosis at bone marrow examination ranged from malignant hematological diseases, benign hematological diseases to nonhematological diseases like storage disorders and visceral leishmaniasis. Thus, our study concludes that bone marrow examination is an important diagnostic tool for various diseases.