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STIM1 and ORAI1

STIM1 and ORAI1
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)...

Tubular Aggregates

Tubular aggregates in H&E stain of muscle/nerve biopsy
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 can provide the neuropathologist with much information, including clues as to the ultrastructural abnormality of this myopathy. Electron microscopy was pursued. Using the images, what is the ultrastructural abnormality shown below in this skeletal muscle biopsy?   Formalin-fixed paraffin-embedding (FFPE) tissue section of skeletal muscle with Tubular Aggregate Myopathy (TAM) demonstrating four nearby muscle fibers with round to ovoid eccentric and subsarcolemmal...

Modified Gomori Trichrome (MGT)

Modified Gomori Trichrome (MGT)
Considering the clinical vignette from the prior week (elderly male with proximal muscle weakness). Staining the skeletal muscle biopsy in combination with Modified Gomori Trichrome (MGT) and oxidative stains can provide the neuropathologist with much information, including clues as to the ultrastructural abnormality of this myopathy. Using the images below, True or False:  The Modified Gomori Trichrome (MGT) staining in this skeletal muscle biopsy is definitive for mitochondria.   Frozen sections of skeletal muscle with Tubular Aggregate Myopathy (TAM) demonstrating two near by muscle fibers with round to ovoid eccentric and subsarcolemmal inclusion-type material with dense bright fuchsinophilic (red) staining...

Myopathy with Tubular Aggregates

Myopathy with Tubular Aggregates
Considering the clinical vignette from last week (elderly male with proximal muscle weakness). Staining the skeletal muscle biopsy with myoadenylate deaminase (MAD) can give the neuropathologist more information than just it’s presence or absence, as may be seen in adenosine monophosphate deaminase (AMPD) deficiency. Using the images, what other structures or ultrastructural clues can be yielded from myoadenylate deaminase (MAD) staining in this skeletal muscle biopsy?   Frozen sections of skeletal muscle with Tubular Aggregate Myopathy (TAM) demonstrating a cluster of muscle fibers with ovoid eccentric to subsarcolemmal basophilic (blue) inclusions (1) with routine hematoxylin and eosin (H&E) stain, and...

Tubular Aggregate Myopathy

A 75-year-old male presents with progressive generalized muscle weakness, issues with balance, back pain, as well as numbness and tingling in the bottom of his feet.  Physical exam shows motor strength 4+/5 with good tone and without atrophy, asymmetry, or fasciculations.  Hand grip and hip flexor strength is decreased.  Shoulder girdle strength is stable.  Sensory exam shows decreased proprioception, vibration, and light touch.  The patient's past medical history includes peripheral neuropathy, type 2 diabetes mellitus, hyperlipidemia, and hypertension.  Prior alcohol use is reported.  EMG/NCS shows electrodiagnostic findings of polyneuropathy.  CPK is reportedly in the normal range.  Skeletal muscle biopsy is...

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...

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...

Renaut Body

Renaut body, neuro notes, muscle biopsy, neuropathology
Figure 1: Cross section of sural nerve with Renaut Body (arrow) and background moderate diffuse axonopathic process.  Plastic embedded thick section stained with Toluidine blue, original magnification x400. A 65-year-old female presents with complaint of numbness and tingling in her hands and feet with gradual progressive onset. She is diabetic, and clinical work-up shows no positive autoantibodies. Nerve conduction studies show electrodiagnostic findings of a mixed sensory and motor polyneuropathy.  The clinical differential diagnosis includes diabetic polyneuropathy versus chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).  A sural nerve biopsy is performed.  What is the structure indicated by the arrow in this image...

Denervation MCQ

Denervation MCQ, Denervation type changes, neuropathology, neuro notes, arkana laboratories
Frozen section of skeletal muscle stained with nonspecific esterase. (Original magnification:  100x) A 45-year old male firefighter with diabetes mellitus presents with chief complaint of lower back pain, right proximal thigh weakness, and minimally elevated CPK. Spine imaging shows multi-level degenerative joint disease and moderate spondylolisthesis.  A skeletal muscle biopsy is obtained from the patient’s right thigh.  What findings are seen in the esterase stained frozen section shown of the right rectus femoris?   Answer: The findings are those of mild active/ongoing denervation-type change. The muscle fibers of interest are variably atrophic and acutely angulated with a suggestion of a...

Satellite Cells

Satellite Cells, Neuro Notes, neuropathology, arkana laboratories
An adult patient with proximal muscle weakness presents with CK 4400 and skeletal muscle biopsy of the thigh shows frequent regenerating and necrotic muscle fibers. In this electron micrograph of skeletal muscle, what are the structures indicated by the black arrows? Satellite cells are a normal population of undifferentiated cells within a skeletal muscle fiber that is capable of differentiating into myoblasts (i.e. stem cell-like properties), hence providing a source to produce new myotubes, as well as regeneration after injury (i.e. necrotizing myopathy).  The figure demonstrates satellite cells between the basal lamina and plasma membrane.  One of the satellite cells...