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The Microscopic study

The description should be in "inverted pyramid", detailing the findings from lower to higher magnification, and always with the most important changes at the beginning and the minor ones at the end. Histological aspects that are not found should be avoided.

To make an orderly description following the histological elements of the organ. For example, in the case of skin, epidermis, dermis with its associated structures - pilosebaceous complex, sweat glands, vessels, cutaneous muscle (according to skin areas and species) and nerve endings - and adipose panniculus.

Histological description of non-neoplastic lesions

  • Should include the organ or tissue (e.g. breast tissue).
  • The first sentence is the most important and should talk about the location and distribution of the lesion in the organ and its size. For this the lowest magnification of the microscope is used.
  • Histological components: name them all but from most to least important.
    Cellular components: name these cells and order them from most to least abundant and indicate their predominance. E.g.: presence of an intense infiltration of neutrophils and macrophages, being more scarce lymphocytes and plasma cells (pyogranulomatous inflammation).
    Non-cellular components: fibrin, edema, hemorrhage, connective tissue, necrosis, etc.
  • If the process is infectious, the causative agent should be described if it is visible with routine techniques: location (intra- or extracellular), size and shape, interpretation (bacillus or cocci type bacteria, fungal hyphae, parasites) and if they are inclusion bodies specify where they are (intracytoplasmic or intranuclear) and color (basophilic, eosinophilic or amphophilic).

Histological description of neoplastic lesions

  • Name the organ or tissue.
  • Description at low magnification: this is the most important part, it includes the location of the neoplasm, the boundaries (demarcated or poorly demarcated, including the capsule), the cellularity (high, medium, low) and the growth pattern (expansive or infiltrative).


  • Cell organization:
    Epithelial tumors: forming papillae, nests, aggregates, tubules, acini or solid growths.
    Mesenchymal tumors: arrangement in bundles, waves, tracks.
    Round cell tumors: in sheets, scattered, monolayer, etc.
  • Cytologic features: cell shape (oval, round, polygonal), size, outline (well or poorly defined), cytoplasm (quantity, color, appearance), nucleus (shape, size, location in cell, chromatin appearance, nucleolus - number, color and evidence). Variations in cell size and shape: anisocytosis, anisokaryosis, karyomegaly, cell pleomorphism, multinucleation, etc.
  • Mitotic index.
  • Malignancy criteria: necrosis, capsule invasion, vascular invasion, infiltrative growth, non-demarcated lesion, etc.
  • Other characteristics: such as inflammation, mineralization, foci of hemorrhage, intense edema, lymphangiectasia, etc.


Quantity (scanty, abundant, etc.) and type (fibrous, fibrovascular). Increased connective tissue in tumors is called desmoplasia.