Bone Marrow Granuloma: A retrospective study

Abstract

Introduction: Granulomas in the bone marrow are rare. Infections, inflammatory disorders and malignancy are known causes. While previous studies have shown tuberculosis to be a common cause, there is variability, with a more recent study showing sarcoidosis predominates. With no local data, this study aimed to determine the causes for granulomas in an Australian population. Methods: Marrow samples with granulomas were identified from 2004 to 2013. The patient histories were examined for known underlying primary conditions, other comorbidities, ancillary testing to determine the aetiology of the granulomas and medications. A proportion was examined to confirm the presence and morphological features of the granulomas. The most likely and alternative potential causes were determined from these results. Results: During the ten year period, 5660 bone marrow biopsies were performed for histology, of which 79 (1.4%) biopsies from 70 patients demonstrated granulomas. B cell non-Hodgkin lymphoma (NHL) was the most common major cause for granulomas in our cohort with 16 (22.9%) cases. Myeloma and Hodgkin disease each accounted for 6 (8.6%) cases and T cell NHL 5 (7.1%). Acute myeloid leukaemia (2), myelodysplastic / myeloproliferative (4) and carcinomas (2) were also seen. There were 44 samples taken from patients with malignancy, of which 35 (80%) had active disease, but only 22 (50%) showed evidence of malignancy in the marrow, indicating a response to systemic inflammation rather than direct marrow involvement. There were 12 (17.1%) cases with sarcoidosis. Autoimmune conditions were considered the primary cause in 6 (8.6%) of cases, however a further 6 patients had autoimmunity in conjunction with another primary condition, typically lymphoma. Infections were seen in a minority of patients. There were two with Mycobacterium avium, both in association with HIV, one with CMV in association with post-transplant lymphoproliferative disorder and another with HIV and Hodgkin disease. There were no cases of tuberculosis. One case was seen in association with Chlamydia pneumonia pneumonitis. Amiodarone was considered the cause for granulomas in three cases. Only 2 cases had no cause identifiable, but 22 cases had more than one potential cause. Conclusions: In this cohort, malignancies predominated as a cause for granulomas. Understanding evolving patterns of disease causation can help most appropriately direct investigations. Show more