Urine Immunofixation Electrophoresis for Diagnosis of Monoclonal Gammopathy: Evaluation of Methods for Urine Concentration.

BACKGROUND: Examination of urine by immunofixation electrophoresis (UIFE) is one of the tests recommended for screening and monitoring of monoclonal gammopathies, especially multiple myeloma. Unlike the serum free light chain measurement, a positive result on urine immunofixation is diagnostic for monoclonal immunoglobulin light chains. Urine is usually concentrated, generally by membrane filtration, prior to electrophoresis. METHODS: Alternative methods to membrane filtration for urine concentration were examined. Residual urine specimens submitted for urine protein electrophoresis were concentrated by precipitation of the proteins by ammonium sulfate salt precipitation, precipitation with ethanol and acetonitrile, and by desiccation. The concentrated specimens were subjected to immunofixation electrophoresis using antisera to free light chains (FLC). The results were compared with those from conventional immunofixation electrophoresis using specimens concentrated by membrane filtration. RESULTS: Ammonium sulfate, ethanol, and acetonitrile precipitation results were less than satisfactory. Concentration by desiccation provided results comparable, if not better than, those by membrane filtration and conventional UIFE. The cost of desiccation is minimal compared to more than $5.00/specimen cost of concentration by membrane filtration. The differences in the results with conventional UIFE and the method described here are likely due to (a) variability in the reactivity of different antisera to free monoclonal light chains, and (b) obscuration of monoclonal free light chains by co-migration with intact immunoglobulin monoclonal proteins. CONCLUSIONS: Concentrating urine by desiccation for immunofixation electrophoresis is technically simple, inexpensive, and provides results comparable to concentrating by membrane filtration. Using FLC provides a more sensitive assay than using conventional antisera.

Late-presenting with a tumor-like mass giant cell reaction related to retropubic midurethral sling.

Stress urinary incontinence (SUI) is a condition that most commonly affects aging women. Synthetic mid-urethral slings (MUS) have become the most common surgical treatment for SUI; however, complications such as mesh erosion and dyspareunia have been reported. This case report describes an 84-year-old female who presented with a tumor-like mass giant cell reaction surrounding the MUS and the management of this mass.

A Rare Presentation of Sarcoidosis Masquerading as Colonic Polyps on Screening Colonoscopy.

Sarcoidosis is a systemic disease characterized by noncaseating granulomatous inflammation. Gastrointestinal involvement in sarcoidosis is a very rare occurrence, with the colon being affected in few patients. We present a case of sarcoidosis presenting as multiple colonic polyps found on routine colorectal cancer screening colonoscopy. Histopathology of the polyps showed noncaseating granulomas.