[Differentiation of granulomatous lesions in the bone marrow]

Granulomas in bone marrow biopsies: clinicopathological significance and new perspectives

Bone marrow granulomas in trephine biopsies are a rare and usually incidental finding. Possible causes include infectious (especially tuberculous and rarer non-tuberculous mycobacteria, but also many other bacterial, viral, fungal and parasitic agents) and non-infectious causes (especially medications, autoimmune disease, sarcoidosis, haematological and non-haematological malignancy). Necrotising granulomas are generally suggestive of an infectious aetiology (tuberculosis being the most common), whereas fibrin ring granulomas are associated with Q-fever and Epstein Barr Virus, although exceptions are possible. Every case suspicious for infectious aetiology should undergo further analysis like special staining (Ziehl-Neelsen for acid-fast rods) or molecular studies. The histomorphology should always be clinically correlated. In cases in which no infectious cause can be identified, untargeted metagenomics may represent a valid diagnostic tool that may become standard in the near future for bone marrow diagnostics. In this review, we have analysed the published data from 1956 up to today, and we report aspects of epidemiology, aetiology, diagnostic algorithms, differential diagnosis and the role of metagenomics in bone marrow biopsies with granulomas.

Bone marrow granulomas in a high tuberculosis prevalence setting: A clinicopathological study of 110 cases

Granulomas were reported in 0.3% to 3% of bone marrow biopsies. The aim of the study was to evaluate the incidence and etiology of bone marrow granulomas (BMGs) in the West China Hospital, which located at a high tuberculosis (TB) prevalence area in China.A retrospective case review was performed on 11,339 bone marrow biopsies at the West China Hospital of Sichuan University between January 2011 and December 2015. Cases with BMGs were retrieved and their clinical data and histopathological features were collected, examined, and analyzed.Out of 11,339, 110 cases showed granulomatous lesions in the bone marrow biopsies (0.97%). Etiologies were indentified in 80 cases (72.8%), with infections being the most common (64.5%), following by malignancies (4.5%) and autoimmune diseases (3.6%). Among infectious cases, 87.32% (62/71) cases were diagnosed as TB, a positive acid-fast stain or/and polymerase chain reaction (PCR) result for mycobacterium TB DNA fragment amplification was obtained for 35 cases. In 30 cases (27.27%), a definite diagnosis could not be established.In a TB high prevalence region in China, with a combined histological, clinical, serological, and molecular approach, we were able to clarify the cause in 72.73% of the bone marrow granulomatous cases. TB is the most common underlying etiologies. Therefore, acid-fast stain and quantitative PCR for mycobacterium TB DNA amplification are recommended as a routine for bone marrow biopsies in TB high prevalence regions.

A Case Report of Pediatric Brucellosis in an Algerian Immigrant

An 8-year old girl presented to our facility with a 10-day history of fever, fatigue, abdominal pain and refusal to walk. She recently travelled from her native Algeria where she first developed symptoms. On evaluation, she was ill-appearing, febrile and tachycardic with hepatosplenomegaly and lymphadenopathy noted on examination. A strong musty odor was also noted from the child. Laboratory evaluation revealed pancytopenia, hyponatremia, and an elevated AST, ALT, and LDH. Malaria testing was negative, as was a PPD. On further questioning, the family reported multiple sick contacts in Algeria with similar symptoms. After discussion with Oncology and Infectious Diseases, she underwent a bone marrow biopsy that was significant for multiple non-caseating ring granulomas. She was started on combination therapy of doxycycline and for presumed brucellosis infection with improvement in her symptoms and resolution of fever. Bone marrow culture returned several days later positive for Brucella melitensis.

Epstein-Barr virus infection associated with bone marrow fibrin-ring granuloma

We previously reported 24 cases of marrow fibrin-ring granuloma (FRG) encountered in 1 institution and concluded that, contrary to previous studies showing marrow FRG as a diagnostic marker for Q fever, Epstein-Barr virus (EBV) was the most common proven cause of such FRG. The present study characterized patients with EBV-associated marrow FRG. We retrospectively reviewed 17 cases of EBV-associated FRG (43% of 40 cases with marrow FRG) diagnosed by bone marrow biopsy. Patients with EBV-associated hemophagocytic lymphohistiocytosis (5/17 patients) and chronic active EBV infection (4/17) constituted 53% of patients with EBV-associated FRG. Three patients had lymphoma without marrow involvement. All patients except 1 presented first with fever; splenomegaly was the next most common clinical finding (12/17). Cytopenia was observed in the 17 cases: anemia in 16, thrombocytopenia in 9, and leukopenia in 8. Patients with EBV-associated FRG showed lower survival outcomes than did patients without EBV (median, 3.0 vs 11.8 months; P = .009). Patients with bone marrow FRG accompanied by fever require careful evaluation to discern whether active EBV infection is involved because the prognosis is poor.