Comparative study of bone marrow clot section with bone marrow aspiration smears in various haematological conditions

Introduction

Aspiration of the bone marrow is very common procedure in haematology practice.1 Bone marrow examination is a very useful investigation and helps in diagnosis of various haematological diseases.

Bone marrow studies not only aid in diagnosis but also staging and monitoring of various diseases, follow up of patients on chemotherapy, transplant and other form of medical treatment.2, 3

Marrow can be involved by metastatic tumour which affects the clinical treatment and prognosis. Bone marrow examination is indeed beneficial, in cases where malignancy are not suspected clinically and is useful in detecting non hematologic malignancies. Bone marrow aspirate smears are used primarily for the assessment of differential count, (M: E) myeloid erythroid ratio, maturation status and morphological details. In addition, biopsy is usually performed to study architecture of marrow and to look for cellularity, fibrosis in conditions like lymphoma, myeloma, metastatic tumour or granulomas, where the involvement can be focal.4

The blood that is obtained along with the bone marrow aspirate is usually discarded though it can be used to prepare a clot section, similar to cell block that is extensively used in cytological practices.5

Bone marrow aspirate clot technique is not being frequently utilized in clinical practice though it has been described in literature. Very few studies have assessed its role in diagnosis and follow up in various haematological diseases. Hence the present study was conducted to evaluate the role of paraffin embedded clot section in diagnosis of various marrow disease and to evaluate the complementary role of both procedures when they are done simultaneously and also to see the advantage and disadvantage of this procedures.

Materials and Methods

This study was done on 30 cases in which had peripheral blood smear, bone marrow aspiration and cell block were included in the study. Bone marrow aspiration was performed clot section was prepared from the blood left over after aspirate smears have been made. Blood containing admixed marrow particle is transferred to container with 10% formal saline for fixation and further processing is carried out as for routine histopathology specimen. Cell block was prepared and stained with H&E and aspiration smears were stained with Leishman stain.

Observations

Total 30 cases were selected in which complete peripheral smears, bone marrow aspirate and cell blocks were available. The findings obtained are as follows (Table 1, Table 2, Table 3).

Results

The present study was conducted for comparison between Bone marrow aspirate smears stained by Leishman and Paraffin embedded cell block section stained by Haematoxylin and Eosin stain. Out of 30 cases there were 20 cases (66.66%) of anaemias, 04 cases (13.33%) lymphoid neoplasms, 04 cases (13.33%) Acute leukemia, 01case (3.33%) MPD, 01case (3.33%) Metastatic deposit. In 09 cases i.e. 30% cell block was unsatisfactory.

The comparison between bone marrow aspiration and bone marrow clot sections are shown in Table 4.

Discussion

The present study was undertaken to assess the efficacy of paraffin embedded cell block of the bone marrow aspirate in comparison with bone marrow aspirate smear in diagnosis of various haematological disorders.

Megaloblastic anemia was the commonest lesion in the present study. Megakaryocytes, eosinophil precursors and megaloblastic changes were better appreciated in cell blocks (Figure 1, Figure 2). Megaloblastic anemia was most common in the age group of 41-50 years and showed male:female ratio of 1.3:1, which was similar to the studies done by Kuperan, Rajshekar Swamy et al.6 in which commonest age group was 31-40 years with male to female ratio of 1.3 :1.

Figure 1

BMC showing Megakaryocytic precursor and eosinophilic precursors H&E (oil immersion)

Figure 2

BMC showing Megaloblastic changes. H&E (oil immersion)

The present study showed male predominance 3 cases (75%) of acute leukemia, which is in similar to Jaishree Sharma and Shoba Mahindrao et al.7 which showed male preponderance 20 cases (55.5%).

Sitalaxmi et al.,8 found that diagnosis of acute leukemia could be done on aspiration alone. Trephine biopsy provided additional useful information. In the present study also acute leukemia were diagnosed on aspiration alone clot section should be used as an adjuvant to bone marrow aspiration to increase the diagnostic yield (Figure 3).

Figure 3

BMC showing leukemia. H&E (oil immersion)

In the present study 4 cases of lymphoid neoplasm which had 2 cases of Hodgkin’s lymphoma, 1 case of Multiple myeloma and 1 case of NHL. In the study by Goyal et al.,9 they found aspirate high sensitivity for acute leukemia (89.4%), Multiple myeloma (88.5%) moderate for NHL (67.6%) and non-hematopoietic metastasis (58.3%) and low for aplastic anemia (38.5%) and Hodgkin lymphoma (5%). Aspiration had no role in granulomatous myelitis and myelofibrosis. Condition like lymphoma, multiple myeloma, metastasis tumours and granulomatous disorders may have focal bone marrow involvement. Bone marrow aspirate alone in these condition may result in false negative diagnosis and an added trephine biopsy sometime from two sites is vital to establish the diagnosis.9

Bone marrow aspiration and paraffin embedded clot section are still very useful tools in diagnosis of unsuspected non haematological malignancies. But in our present study one case of metastasis was diagnosed on aspirate but clot section was unsatisfactory (Figure 4).

Figure 4

BMC - Unsatisfactory smear

But in cases of Naveen Kakkar et al.,10 diagnosed a case of Relapse of multiple myeloma with clot section alone with negative bone marrow aspirate and trephine biopsy.

Clot section can also be used for specialized procedure like immunohistochemistry. Compared with trephine biopsy section, clot have a better antigen retrieval for immunohistochemistry as decalcification is not required. In situ hybridization studies too have shown better results with clot section as compared to conventional trephine biopsy.2

In the study by Jasim et al.11 81% of cases marrow clot sections were diagnostic. However, trephine was still necessary in 19% of cases in whom the clot sections were of poor quality and unconvincing. In present study clot sections were unsatisfactory in 30% of cases which were of poor quality composed of blood clot only or with few scattered hematopoietic cells. Because it will be difficult to anticipate which patient will be diagnosed by clot section so it would be advisable to combine clot section along with bone marrow aspirate and biopsy as an adjuvant procedure to increase the diagnostic yield.

Conclusion

The study concludes that preparation of bone marrow aspirate and clot section is easy, rapid and complementary to each other in majority of lesions. Megakaryocytes and eosinophilic precursors can be better appreciated in cell block, further cell block can be stored and used for specialized procedures like IHC. The advantages of both procedures done together improves the diagnostic yield.

Source of Funding

None.

Conflict of Interest

The authors declare that there is no conflict of interest.