Fever, Pancytopenia and Intracellular Eukaryotic Microorganisms in a Bone Marrow Aspirate
- 1. Department of Parasitology and Mycology, Pitié-Salpêtrière Hospital, France
- 2. UMRs945 INSERM-Pierre et Marie Curie University, France
- 3. Center of Immunology and Infectious Diseases, CIMI-Paris, France
- 4. Sorbonne Universities, UPMC University Paris VI, France
- 5. Laboratory of Excellence GR-Ex, Paris, France
- 6. Department of Internal Medicine, Pitié-Salpêtrière Hospital, France
Citation
Mouri O, Fekkar A, Gille AS, Marc T, Amoura Z, et al. (2017) Fever, Pancytopenia and Intracellular Eukaryotic Microorganisms in a Bone Marrow Aspirate. Ann Clin Cytol Pathol 3(7): 1082.
CLINICAL IMAGE
A 58 year-old female from Cambodia travelling to France for Waldenström’s macroglobulinaemia treatment. She had systemic lupus erythematosus and anti- phospholipid syndrome with history of sub-acute fever, corticosteroid-responsive prolonged thrombocytopenia associated with immunosuppression induced by chemotherapy. She was admitted to the hospital for nonobstructive acute pyelonephritis. The laboratory findings revealed pancytopenia with moderate anemia (hemoglobin 8.7 G/dL), leucopenia (white blood cell count 3.64 109 /L), and severe thrombocytopenia (6.109 /L) initially attributed to late toxicity of chemotherapy, thrombocytopenic purpura, or macrophage activation syndrome. Culture of blood and urine samples did not yield bacteria and testing for human immunodeficiency virus were negative. Smears from a bone marrow aspirate were prepared and stained with Wright-Giemsa (Figure 1A) showing a moderate cell density with megakaryocytes and numerous macrophages in the cytoplasm of which, intracellular 2 μm-long bodies with internal purple staining suggestive of a nucleus were observed. Treatment with liposomal amphotericin B was started and symptoms resolved with a rapid clinical improvement. The patient remained completely asymptomatic with normal laboratory parameters 1 month post treatment. The microscopic aspect was highly suggestive of histoplasmosis. Silver staining of bone marrow smears and à culture that resulted positive a few weeks later confirmed the diagnosis of disseminated histoplasmosis.
DISCUSSION
The observation of 2-4 µm oval, narrow-based budding elements on Wright-Giemsa stained smears is highly suggestive of histoplamosis. However, other micro-organisms resemble H. capsulatum in tissues [1]. Histoplasma capsulatum, Leishmania donovani s.l. and Toxoplasma gondii are the three main eukaryotic microorganisms that can cause sub- acute fever with pancytopenia. Both L. donovani and T. gondiican display morphological aspects similar to yeasts of H. capsulatum on a Giemsa-stained smear. Pseudo- capsulated H. capsulatum (Figure 1.A, arrowhead) and L. donovani amastigotes that infect human macrophages are similarly ovoid, and are almost identical in size (Figure 1.C). Robust morphological identification of Leishmania amastigotes requires the association of à cell membrane, a basophilic staining nucleus and à rod-shaped intensely stained kinetoplast (Figure 1.C, arrowhead). T. gondii tachyzoites rapidly invade and multiply in many mammalian cell types and are sometimes observed in human macrophages. They are crescent-shaped, approximately 5-7 µm long, with pale blue staining cytoplasm and pink nucleus (Figure 1.D, arrowhead). Silver staining of smears confirmed the diagnosis of histoplasmosis by showing the yeast wall (Figure 1.B, arrowhead). Silver does not stain protozoan plasma membranes. The diagnosis was further consolidated by a serum positive Aspergillus galactomannan index which is known to cross react during invasive histoplasmosis and, a few weeks later, by the appearance of H. capsulatum hyphae with microconidia and characteristic tuberculate macroconidia formed on short, hyaline, undifferentiated conidiophores in culture (Sabouraud medium, 25°C, under humidified, aerobic conditions, strict confinement). PCR analyses for T. gondii and Leishmania spp were both negative. Treatment of disseminated toxoplasmosis is with either pyrimethamine-sulfonamide or cotrimoxazole [1,2]. The first-line treatment of both disseminated histoplasmosis and visceral leishmaniasis is liposomal amphotericin B, but regimens differ. In India, a single infusion of 10 mg/kg cures visceral leishmaniasis due to L. donovani in more than 95% of cases [3], whereas a longer induction therapy with higher cumulative dose followed by maintenance therapy with azole therapy is essential for sustained cure of disseminated histoplasmosis [4,5]. The patient had a sustained response to treatment with liposomal amphotericin B, followed by oral azoles (itraconazole switched to posaconazole after 14 days) for one year. Immediate microscopic identification of Histoplasma capsulatum facilitated a prompt, adapted treatment without waiting for the results of antigen/ antibody detection, PCR and culture.