18A199

Necrotising Prostatitis – An Unusual Presentation of IgG4 Related Disease

Author(s)

Rajneet Singh1, Fatemah Baron1, Thomas Fitzgerald2, Vincent Tormey3, Bernadette Lynch1

Department(s)/Institutions

1Department of Rheumatology, University College Hospital Galway (UCHG) 2Department of Pathology, University College Hospital Galway (UCHG) 3Department of Immunology, University College Hospital Galway (UCHG)

Introduction

IgG4 Related Disease (IgG4RD) is a recognised immune-mediated condition of unknown cause. It can present with myriad of clinical manifestations with multi-organ involvement. Prostate involvement with IgG4RD is very rare.

Aims/Background

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Method

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Results

A 58 year male presented to the urology service with worsening urinary frequency, hesitancy and nocturia in the setting of a normal prostate-specific antigen (PSA) test. There were no other systemic features associated with the acute onset. The patient was initially treated for benign prostate hyperplasia (BPH) and underwent transurethral resection of the prostate (TURP). Post-operatively, he continued to have difficulty voiding. MRI prostate was consistent with heterogeneous enhancement of the prostate with some inflammatory changes noted in the proximal urethra. Histopathology revealed florid fibrovascular connective tissue infiltration with necrotising inflammatory reaction.
Due to a raised C-reactive protein (47mg/dl), neutrophilia and positive urine culture for E.Coli, he was treated for possible infectious prostatitis with 6 weeks of intravenous Meropenem. Extensive workup including a vasculitis screen, syphilis, HIV and TB culture was negative. Inflammatory markers improved with 6 weeks of antibiotic.
A few weeks post discharge, he represented with urinary retention and prostatic pain and underwent a second TURP. A repeat MRI prostate at that stage was consistent with acute severe inflammatory prostatitis with multiple localising abscesses and histopathology was suggestive of extensive acute and chronic inflammation and foci of coagulative necrosis. Patient reported good response to prostatic pain with glucocorticoids and a rheumatology opinion was sought. A number of additional tests were arranged including immunoglobulin IgG subclasses which were mildly raised at 1.42g/l with a normal serum protein electrophoresis. Immunohistochemical staining of the two previous prostate biopsies for IgG4, revealed extensive staining of plasma cells for the IgG4 antibody with up to 60 positive plasma cells per high power field. A diagnosis of IgG4RD was confirmed and the patient commenced on high dose steroid with a plan to start Rituximab.

Conclusions

IgG4RD can mimic many malignant, infectious, and inflammatory disorders. The key to diagnosis is histopathology suggestive of extensive infiltration of IgG4 positive plasma cells in tissues, with dense lymphoplasmacytic infiltrate, storiform fibrosis and oblierative phlebitis.