school-of-fish appearance

school-of-fish appearance

A descriptive term for a light microscopic pattern characterised by multiple, discrete oval-to-elongated structures arranged in long roughly parallel fascicles.
 
Microbiology
A fanciful term for the light microscopic appearance of the gram-negative bipolar-staining coccobacillus, Haemophilus ducreyi, the chancroid agent.
 
Pathology
A term referring to the “haphazardly parallel” arrangement of fascicles of malignant cells in fibrosarcoma, commonly known as a storiform pattern. Such lesions may be circumscribed—but non-encapsulated—masses with microcyst formation within skeletal muscle or soft tissue; they are composed of monophasic basophilic spindled tumour cells in haphazardly arranged fascicles, with focal hemangiopericytomatous vascularity and dense cellularity, admixed with paucicellular myxoid areas. The cells are relatively small, with overlapping ovoid pale nuclei. Mitosis may be seen.  

DiffDx
Fibrosarcoma, hemangiopericytoma, leiomyosarcoma, monophasic synovial sarcoma, MPNST, solitary fibrous tumour.
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