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Diagnose This (April 19, 2021)

AA Amyloid Diagnosis in Renal Biopsy
What is your diagnosis in a 35 y/o male with paraplegia and chronic osteomyelitis who presents with nephrotic syndrome? Bonus: What subtype would you suspect based on the clinical history?     ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​  ...

Anti-SRP Myopathy with Chronicity

Anti-SRP Myopathy in neuro muscle biopsy
The patient is an 80-year-old female who presents with chief complaint of progressive proximal muscle weakness and carries a clinical diagnosis of polymyositis for nearly two decades. She was placed on a maintenance dose of steroids and was lost to follow-up for several years. No statin medication is reported.  She was recently admitted after a wellness check revealed that she was unable to ambulate independently.  CPK values ranged from 1500-7700.  A skeletal muscle biopsy of the left thigh was performed.  A follow-up myositis serology panel showed a positive anti-signal recognition particle (+ anti-SRP).  Using the images, what’s your diagnosis for...

Twitter Poll (April 14, 2021)

sickle cell nephropathy, Crescents
Answer: Crescents   Sickle cell disease is an autosomal recessive disorder classically seen in African-Americans which is caused by a single nucleotide change on chromosome 11p15.5 resulting in an amino acid change from glutamic acid to valine. In the kidney, the disease manifests as sickle cell nephropathy. Histologic features seen in this disease include focal segmental glomerulosclerosis, glomerular enlargement, double contour formation, and hemosiderin deposition within tubular epithelial cells to name a few. Crescent formation is not typically seen in sickle cell nephropathy and if seen would be worrisome for a concomitant process (i.e. ANCA-associated glomerulonephritis).      


Considering the clinical vignette from the prior week (elderly male with proximal muscle weakness). Staining the skeletal muscle biopsy with Hematoxylin and Eosin (H&E) in combination with frozen sections evaluated with Modified Gomori Trichrome (MGT) and oxidative stains, as well as electron microscopy, demonstrated findings diagnostic of myopathy with tubular aggregates (TAM). See the images.  Mutation in which of the following genes is associated with myopathy with tubular aggregates?   Frozen tissue section of skeletal muscle with Tubular Aggregate Myopathy (TAM) demonstrating two adjacent muscle fibers with round to ovoid eccentric and subsarcolemmal inclusion-type material with dense granular basophilic (blue)...