57 year old man with positive Jo1 antibody and interstitial lung disease. H&E shows necrotic fibers and myophagocytosis predominantly involving perifascicular fibers. The perimyisial connective tissue appears edematous and fragmented.
A monophasic sarcomatoid carcinoma shows only a spindle cell component with mesenchymal appearance, without admixed carcinoma. Extensive sampling and history of prostatic adenocarcinoma, preferably with immunohistochemical (keratins, rarely PSA or other prostatic markers) evidence of epithelial differentiation, helps establish the diagnosis.
Advanced decidual arteriopathy with fibrinoid necrosis. Arteries are distended and show endothelial injury (detachment from the wall, arrow) and fibrinoid necrosis of the media (*). 200x original magnification.
Infarction (fresh): infarcts are typically pyramidal shape and involve the maternal floor of the placenta. Older infarcts are white, while more recent infarcts are red / heterogeneous in the fresh state.
Thigh muscle from a 49 year old woman with progressive proximal weakness and creatine kinase in the 7,000s. Histology shows a pauci-inflammatory IMNM. The necrotic fibers are randomly distributed and temporally heterogeneous. There is also moderate fiber size variation and frequent internalized nuclei, suggesting that myofiber damage has been going on for a while (H&E, 20x).
Cytomorphologically, lesional cells are highly bizarre and atypical, with marked pleomorphism in size and shape, abundant eosinophilic cytoplasm, occasional multinucleation and numerous mitotic figures, including atypical forms (H&E, 200x).
Bone marrow biopsy from a patient with aCML showing markedly hypercellular bone marrow with markedly increased neutrophils and myeloid precursors and mild dysmegakarypoiesis with no increase in blasts.