Methods (Differential Diagnosis, Investigations and Treatment):
A complete blood count (CBC) showed leukopenia at the expense of severe neutropenia, mild normocytic anemia, and normal platelets.
Table 1 shows the initial lab results for the patient. (separate File)
Differential Diagnosis included infections, sarcoidosis, systemic lupus erythematosus, and myeloproliferative syndromes. Further workup was carried out to determine the cause of decreased neutrophil count. A chemistry panel showed paraproteinemia, normal kidney function, and normal liver enzymes. The infectious panel showed a negative rapid COVID test, HIV negative, hepatitis C antibody test non-reactive, and serologic testing for hepatitis B suggested passive immunity. She was found to have a positive antinuclear antibody (ANA) test and a positive rheumatoid factor. The anti-cyclic citrullinated peptide (anti-CCP) was high >340. A peripheral flow cytometry was unremarkable. The patient had a bone marrow biopsy, and aspiration showed a norm cellular marrow with maturing trilineage hematopoiesis, a preserved marrow reserve pool on the two occasions. In addition, there was no morphologic evidence of overt or advanced myelodysplasia, acute leukemia, metastatic neoplasm, plasma cell dyscrasia, or lymphoma.
An ultrasound of the abdomen showed a slightly enlarged liver due to possible fatty infiltration, and the spleen measured 11.8 x 4.5 x 13.6 cm, which was mildly enlarged (Figure 1) (separate File)
Due to the positive RF factor, she was evaluated by rheumatology due to features of Felty syndrome and diagnosed with rheumatoid arthritis. She initially started Prednisone 10 mg daily and later transitioned to Hydroxychloroquine 200 mg qd. Despite treatment, the patient reported only mild improvement in her body aches, but her neutropenia and severe fatigue persisted.
Due to her dropping neutrophil count and peak COVID infection, a joint decision to treat her was made with a trial of prednisone 1 mg/kg daily for two weeks, resulting in the normalization of the absolute neutrophil count (ANC). This response was sustained for four months before relapsing. After stopping steroids, the ANC level again dropped. Rituximab was then considered as an alternative for long-term management of autoimmune neutropenia in the setting of Felty syndrome.
Figure 2 and Figure 3 show the trend of absolute neutrophil count and white blood cell count after treatment with steroids and Rituximab. (In separate Files)