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Fibrous Body

Fibrous Body, neuro path, arkana laboratories, Muscle biopsy
A 75-year-old female patient presents with proximal muscle weakness, characteristic skin rash, and dysphagia. Laboratory workup reveals elevated CPK 3500. A skeletal muscle biopsy is performed from the right thigh and shows findings diagnostic of dermatomyositis.  The muscle biopsy also shows rare vacuolated muscle fibers with Modified Gomori Trichrome stain.  Electron microscopy is pursued.  What is the ultrastructural finding seen in the electron photomicrograph shown below?   Answer: The electron photomicrograph shows a Fibrous (filamentous) body, which is a nonspecific finding that may be seen in a variety of clinical settings, including inflammatory myopathies, such as dermatomyositis, as well as...

Diagnose This (February 22, 2021)

amyloidosis, Amyloid Spicules on Jones Silver Stain, amyloid spicules with eyelashes, renal pathology
What is your leading diagnosis when seeing this finding along the glomerular capillary loops?     ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​   ​ ​   ​...

Congophilic Inclusions

congophilic inclusions, sporadic Inclusion Body Myositis, neuropathology, arkana laboratories, neuro notes
A 68-year-old man presents with insidiously progressive proximal left thigh weakness with atrophy, left foot drop, and right hand grip strength weakness.  Laboratory work-up reveals elevated CPK 850 and negative myositis panel.  A muscle biopsy of the left thigh is performed, and shows a polymyositis-type injury pattern with myofibers containing rare rimmed vacuoles.  Using the movie below, what characteristic finding is seen with Congo red stain in this case? Answer: The images show different modalities examining a Congo red special histochemical stain demonstrating characteristic congophilic inclusions of sporadic Inclusion Body Myositis (sIBM). With a Congo red stain, the skein-like inclusions...