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Twitter Poll (January 20, 2021)

Immunotactoid Glomerulopathy, Immunotactoid, renal pathology, arkana laboratories
Answer: A, Immunotactoid Immunotactoid Glomerulopathy is characterized by parallel microtubular deposits with lucent cores which are classically greater than 30 nm by electron microscopy. Both fibrillary and amyloid fibrils are typically characterized as non-branching randomly oriented fibrils which range usually between 10-20 nm and 7-12 nm, respectively. Light chain deposition disease classically shows characteristic punctate, powdery deposits within glomeruli and tubular basement membranes by electron microscopy.  

Diagnose This (January 19, 2021)

Infection-Associated Glomerulonephritis, diagnose this, arkana laboratories, renal disease of the kidney
Based on the electron microscopic image, what would be your initial underlying clinical concern for the findings seen?       ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​...

Nemaline Rods

Nemaline Rods, neuro notes, neuropathology, Dr. Mrachek
What are these dark (osmophilic) structures seen in this electron micrograph of skeletal muscle?   These osmophilic structures are Nemaline rods (largest, white arrow). These structures are classically seen in "Nemaline Myopathy" (NM; aka rod body myopathy). The rods are located in the sarcoplasm, and may also be seen within nuclei. NM is most commonly caused by dominant mutations of ACTA1 (encoding skeletal a-actin) and recessive mutations of NEB (encoding nebulin).  Intranuclear rods are associated with pathogenic ACTA1 mutations.  There are variable phenotypes of NM ranging from the severe congenital myopathy to adult-onset disease.  Limited numbers of muscle fibers containing...

Diagnose This (January 12, 2021)

antibody-mediated rejection, arkana laboratories, renal pathology, diagnose this, kidney disease
What are the two major changes seen in this image from an allograft kidney and what are these findings concerning for?       ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​...

Sarcomere Bundles of the A Zone

sarcomere, Neuro notes, renal pathology, arkana labs, neuropathology
This week’s interesting image shows the examination of skeletal muscle in cross-section at the level of the A zone by electron microscopy in Figure 1, and corresponding illustration of the sarcomere in longitudinal section, Figure 2. Figure 1. Ultrastructure of sarcomere bundles.  The contractile elements of skeletal muscle are seen in cross-section at the level where myosin thick filaments and actin thin filaments overlap at the "anisotropic" or "A" zone of the sarcomere.  Electron Microscopy (EM): 25000x original magnification. Figure 2.  Illustration of sarcomere bundles.  The sarcomere contractile apparatus viewed in longitudinal section shows various degrees of overlap of the...

Diagnose This (January 4, 2021)

artery with a cholesterol embolus, arkana laboratories, renal pathology, renal disease
What is your diagnosis and what are some possible precipitating events that may lead to this finding?       ​ ​   ​   ​ ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​   ​ ​   ​ ​  ...