Moth-eaten Appearance of the Skull

Derek Little, B.M.Sc, M.D. and Rebecca Kruisselbrink, M.D. MPH 

March 25, 2016

A 61-year-old woman presented to the ER with a one-week history of nausea, back pain, and decreased urine output. She was found to be in oliguric renal failure, with creatinine peaking at 12.1 mg/dL and urinalysis positive for 3+ blood and 1+ protein. A 24-hour urine protein totaled 2.97 g suggesting non-albumin proteinuria, and both serum and urine protein electrophoresis were negative for an M protein spike. Urine Bence Jones proteins, free kappa/lambda ratio, and inflammatory workup were pending, but given the dramatic rate of renal deterioration a renal biopsy was performed. This revealed cast nephropathy with light chain deposition. A skeletal survey revealed multiple, well-circumscribed, lytic lesions in her skull with a prominent lesion suggestive of a plasmacytoma (Figure 1). She had previously presented to several physicians for the mass on her head and was reassured it was benign.

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About the authors:

Derek Little is a third year medical student at McMaster University in Hamilton, Ontario, Canada. He is interested in pursuing a residency in Internal Medicine. 

Rebecca Kruisselbrink, M.D. MPH is a general internist and critical care physician at St. Joseph’s Healthcare in Hamilton, Ontario, Canada. She is a clinical assistant professor in the Department of Medicine at McMaster University.