#00064780

Case presentation:

A 66-year-old female patient presented to the Medicine out-patient department (OPD) with low-grade fever for one week and generalized weakness, breathlessness, and decreased appetite for one month. She had a history of one episode of cerebrovascular accident (CVA) in the past. She is also a known diabetic, hypertensive, and hypothyroid on regular medications. On examination, she had pallor and pedal edema. There was no icterus, lymphadenopathy, or organomegaly noted. Her respiratory, cardiovascular, and central nervous system examination was normal. Her complete hemogram revealed hemoglobin of 82 g/L, total WBC count of 4 x 10⁹/L with absolute neutrophil count (ANC) – 3 x 10⁹/L and platelet count of 56 x 10⁹/L. Peripheral smear findings were suggestive of normocytic normochromic anemia with thrombocytopenia. No abnormal cells/ dyspoiesis were noted in the peripheral smear. Biochemical investigations were performed which revealed serum ferritin of 91 ng/mL, serum vitamin B12 level of 180 pg/mL and serum folate level of 5 ng/mL, all falling within the expected reference range. Due to persistent anemia and thrombocytopenia, there was a clinical suspicion of myelodysplastic neoplasm (MDS), hence our patient was subjected to bone marrow examination.

Bone marrow aspirate smears were cellular and showed active normoblastic erythropoiesis and active myelopoiesis with sequential maturation. No dyspoiesis was noted in erythroid and myeloid lineages. Megakaryocytes were adequate in number and exhibited mild dyspoiesis in the form of monolobated and separated lobe forms. In addition, there were a significant number of neutrophils exhibiting phagocytosed intracytoplasmic eosinophilic, homogenous, nuclear material referred to as LE bodies, resulting in the formation of lupus erythematosus cells (LE cells). Retrospectively, we performed buffy coat preparation from her peripheral blood sample, which also demonstrated the presence of LE cells.

Subsequently, a panel of autoimmune tests was performed which revealed 4+ antinuclear antibody (ANA) by immunofluorescence exhibiting homogenous pattern. Using nephelometry, her complement proteins were measured, revealing decreased C3 levels at 0.59 g/L (with a normal range of 0.9-1.8 g/L) and diminished C4 levels at 0.06 g/L (with a normal range of 0.1 – 0.4 g/L). In addition, our patient also tested positive for lupus anticoagulant (LAC) by diluted Russell Viper venom test (DRVVT). Our patient was diagnosed with systemic lupus erythematosus (SLE) and was started on steroids. The patient's well-being significantly improved along with a notable increase in platelet count.

Learning points:

1. LE cells are neutrophils that have engulfed denatured nuclear material, a phenomenon resulting from opsonization of cells by self-antibodies. These cells are not specific to SLE and can also be observed in a variety of other autoimmune connective tissue disorders. LE cells are usually demonstrated in defibrinated blood, by buffy coat preparation. However, the presence of LE cells in the bone marrow and serous fluids of SLE patients is a rare occurrence, as demonstrated by our case.^1,2

2. In clinically suspected cases, SLE is routinely diagnosed using the current European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria which requires positive ANA titers as an entry criterion.³ In our elderly patient, where SLE was not initially considered a differential diagnosis, the identification of LE cells in the marrow emerged as a vital clue that ultimately led to her diagnosis.

References:

1. Mohammed SJ. Occasional detection of lupus erythematosus cells in bone marrow samples: A case report. Clinical Case Reports. 2021;9:e04470.

2. Sathiavageesan S, Rathnam S. The LE Cell—A Forgotten Entity. Indian J Nephrol. 2021;31:71–2.

3. Aringer M. EULAR/ACR classification criteria for SLE. Semin Arthritis Rheum. 2019;49:S14–7.

Figure Legend:

Figure A, B, C: Bone marrow aspirate smear shows many LE cells (black arrows) which are neutrophils with engulfed intracytoplasmic eosinophilic, homogenous, nuclear material (Giemsa stain, 400x). Figure D: Buffy coat preparation smear showing similar LE cells (Giemsa stain, 400x).