ABSTRACT
The diagnosis of systemic lupus erythematosus (SLE) was a leading initial consideration in 2 patients with rash, arthritis and hypocomplementemia. One patient also had leukopenia and thrombocytopenia. Spontaneous regression occurred. In both patients antinuclear antibodies were negative. Serologic studies indicated recent human parvovirus B19 infection. We propose adding human parvovirus B19 infection to the list of conditions that may masquerade as SLE.
Subject(s)
Erythema Infectiosum/diagnosis , Lupus Erythematosus, Systemic/diagnosis , Adult , Arthritis/microbiology , Complement System Proteins/analysis , Dermatitis/etiology , Diagnosis, Differential , Erythema Infectiosum/blood , Erythema Infectiosum/complications , Female , Humans , Leukopenia/etiology , Remission, Spontaneous , Thrombocytopenia/etiologyABSTRACT
Leukopenia (WBC 1.9 x 10(9)/L) was reported from an automated cell counter (TOA E-5,000, Symex) on a patient blood sample collected in ethylene diamine tetracetic acid (EDTA). Leukocyte aggregates of 30-50 cells were seen on the peripheral blood smear. Blood samples collected in heparin, citrate, and EDTA had white blood counts (WBC) of 8.1, 8.1, and 2.5 x 10(9)/L. A 0.3-mL aliquot of patient EDTA-plasma mixed with 0.3 mL normal packed cells (NPC) resulted in a WBC of 2.7 x 10(9)/L, a reduction of 58% from the control value. Increasing concentrations of EDTA (0.35-2.16 mg/mL), patient serum, and NPC resulted in a greater than 60% WBC reduction at EDTA concentrations greater than 0.96 mg/mL. Serial dilutions of patient serum in phosphate buffered saline (PBS) showed greater than 50% WBC reduction at a dilution of 1:4. Incubation (0, 1, and 2 hours) (0 degrees C, room temperature [RT], and 37 degrees C) of samples containing patient serum, EDTA, and NPC resulted in the greatest WBC reduction at 2 hours and at RT (60%). Incubation with 0.01 M dithiothreitol (DTT) abolished the ability of patient serum to decrease the WBC. These data suggest an EDTA-dependent, low titer IgM leukoagglutinin.
