Practical Flashcards
Cancer
Malignant slides: Can see tumour giant cells.
Metastasis - To a solid organ, core can be necrotic.
Screen for colorectal cancer - Foecal occult blood test and endoscopy.
Ductal carcinoma in situ - Non-invasive adenoma cells in breast ducts.
Leiomyomas in the uterus are also known as fibroids.
Leiomyosarcomas are vascularly rich - spread by blood. They can be so anaplastic that you can’t tell where they’re from if they spread. To work out its a leiomyosarcoma, immunostain for SMOOTH MUSCLE ACTIN.
Alcian blue stain can be used to identify metaplasia; stains mucin blue, metaplastic epithelium has less mucin
Skin squamous carcinoma - Keratin pearls - abnormal squamous cells form concentric layers.
Hypersensitivity
In Hashimoto’s (hypothyroidism, TH1 response - remember ‘Two Many Graves’): Thyroid acini (or thyroid follicles) have an “over-stimulated” appearance with little colloid production (precursor to T3 and T4).
Nasal polyp is due to Type 1 hypersensitivity. Plasma cells, eosinophils, lymphocytes abundant.
For TB, initially, the response is at two separate sites; one is the site of entry, usually the periphery of the lung (which is called the Ghon focus) and the other is within the draining lymph nodes. This pattern is known as the primary complex (Ghon focus + local lymph node involvement).
Macrophages in granulomas (granuloma = collection of macrophages) are enlarged with pink cytoplasm - called “epithelioid” macrophages because they resemble epithelial cells in the large amount of cytoplasm they have. These macrophages are ‘activated’ M1 type which have enhanced killing capacity. Some macrophages fuse together to form “giant cells” with many nuclei.
Large epitheliod cells + Multinucleate giant cells.
In chronic infection, the state caseous necrosis surrounded by attempted healing by fibroblasts laying down collagen is fibro-caseous tuberculosis.
If granuloma ruptures, TB can spread to pulmonary vein and enter circulation. TB can reach meninges and granulomatous inflammation spreads over the surface of the brain (tuberculous meningitis). Spreading around body is called miliary TB.
Mycobacterium tuberculosis itself is not very destructive and yet terrible tissue destruction takes place as the body’s own cells are recruited and themselves die. This process represents Type IV hypersensitivity.
On first exposure, there is rapid spread from the portal of entry to the lymph nodes. On re-exposure usually at apex of lungs where O2 is the highest, the circulating long-lived lymphocytes with “memory” of the antigens immediately recruit other lymphocytes to immobilise and stimulate macrophages with ingested organisms. This means that re-infection may be localised to the site of entry.
Ziehl-Neelsen stain: TB exposed to a hot solution of basic dye to penetrate mycolic acid coat.
M.TB is called acid & alcohol-fast bacilli (AAFB). Resistance to decolorisation by acids and alcohol. Other mycobacteria are acid-fast only.
Read Q8 in Practical 10.
HIV can infect megakaryocytes and thus lead to thrombocytopaenia.
Parasite
Although it does not have a hypnozoite stage, patients infected with P. malariae may have prolonged, asymptomatic erythrocytic infection the becomes symptomatic years after leaving the endemic area.
P. malariae/P. knowlesi: Banded trophozoite, loose clusters of merozoites in schizont. No stippling.
P.ovale + P.vivax: Enlarged and distorted RBCs.
All produce ‘stippling’ - dots in the trophozoite picture, apart from P.malariae/P.knowlesi.
If you see nucleated RBCs, then they come from birds, and it’s caused by P.relictum.
Crescent shaped gametocytes - P.falciparum. Also the schizont and trophozoite pictures won’t show much as P.falciparum sequesters in cerebral blood vessels - nausea, lethargy, vomiting.
Leishmania parasite: Each amastigote has a nucleus + kinetoplast containing DNA. Amastigote enters macrophages. Leishmania disease can recur - it persists in you a long time.
Other Histopathology
Plasma cells have an eccentrically placed ‘clock-faced’ nucleus. Have darkly staining nuclei as it’s making antibodies rapidly.
Macrophage: large phagocytic cells, with a pale C-shaped nucleus and a pale cytoplasm that contains phagocytosed material.
Toluidine blue
Stains mast cells purple.
Cancer
Increases blood coagulability.
