Pancytopenia and splenomegaly as uncommon manifestations in a patient with immunoglobulin G4-related disease.

Haematological manifestations of immunoglobulin (Ig)G4-related disease (IgG4-RD) are atypical, and few studies have addressed cytopenia in this condition. We present here a case of IgG4-RD with marked pancytopenia and splenomegaly in the absence of bone marrow abnormalities. A 67-year-old woman developed diplopia, dyspnoea, pancytopenia, and hypocomplementemia. Contrast-enhanced computed tomography showed bilateral lacrimal and submandibular gland swelling, enlargement of the cervical, mediastinal, inguinal, and para-aortic lymph nodes, splenomegaly, and granular shadows in both lungs. She had been referred to our hospital on suspicion of malignant lymphoma, but a lymph node biopsy indicated the possibility of IgG4-RD. A lacrimal gland biopsy showed infiltration of numerous lymphocytes and IgG4-positive plasma cells along with mild fibrosis. A bone marrow biopsy showed normocellular marrow with no increase in plasma cells. The IgG4-positive plasma cell count was 4 per high-power field, with an IgG4/IgG ratio of 10%. After excluding potential mimics, the diagnosis was IgG4-RD presenting with pancytopenia and splenomegaly. Prednisolone was initiated at 40 mg/day, leading to the rapid normalisation of pancytopenia, recovery of complement levels, and resolution of other organ involvement such as splenomegaly. Physicians should keep in mind that IgG4-RD can present with pancytopenia and splenomegaly.