HAEMATOXYLIN:
- Derived from the wood Haematoxylum campechianum.
- It means bloodwood - refers to the dark red colour (Haemato - blood, xylon- wood)
- Campechianum refers to the coastal city of Campeche on the Yucatan Peninsula, the locality of the heart wood.
Pic: Google
If Haematoxylum is red, how is haematoxylin blue?
- Haematoxylin has little or no staining capacity.
- Haematoxylin is oxidised to haematein which gives the blue colour.
- Oxidation - two methods - 1. Natural 2. Chemical
Haematoxylin versus Haematein:
If hematein is the dye and haematoxylin needs to be oxidised before it can stain, why not use hematein in the first place?
- If we start with hematein, oxidation will start to diminish the staining capacity right from the start, shortening the working life of the solution ☺☺
Mucormycosis
Predisposing factors:
- Transplant recipients
- Uncontrolled diabetes mellitus
- Patients with hematological malignancies
- Immunosuppressed patients
- People living with HIV (PLHIV)
HOW TO IDENTIFY MUCORMYCOSIS:
Broad, aseptate fungal hyphae, branching at 90 degree.
Angioinvasion is frequently seen, leading to thrombosis of vessels and tissue infarction & necrosis.
Mucor is always seen as a basophilic "glassy" structure on H&E staining.
Pic shows fungal hyphae with right angled branching.
PAS and Silver Methanamine stain highlight the fungal hyphae.
Pic: PAS stain
Silver methanamine: Arrow points to the blood vessel, fungal hyphae are seen infiltrating the wall.
DIFFERENTIAL DIAGNOSIS:
ASPERGILLUS:
Slender, septate hyphae with acute angle branching.
Note: Candida species is often seen with Mucor and Aspergillus.
