Fungal
 
Superficial mycoses

1. Superficial mycoses→outermost layers of the skin or its appendages; skin, nails and/or hair.
2. Dermatophytoses transmitted by contact with man (anthropophilic; weak inflammatory response), animals (zoophilic; brisk inflammatory response), or contact with soil (geophilic; strongest inflammatory response).
3. Trichophyton→hair, skin, or nails; Microsporum → hair and skin; and Epidermophyton→skin alone.
4. The diagnosis is best made by culture of skin scrapings secured from the leading edge of the lesion.
 - use Wood's light to check for fluorescing metabolites.
 - direct KOH preparations of the scraped material
 
 Subcutaneous Mycoses
 
1. Subcutaneous mycoses are usually related to traumatic implantation into the skin.
2. Chromoblastomycosis, or verrucous (wart-like) dermatitis, is a chronic skin lesion associated with several pigmented fungi (Fonsecaea, Phialophora, and Cladosporium).
 - granulomatous reaction in subcutaneous tissue are pigmented, thick walled bodies are visible in tissue section.
3. Mycetomas (maduromycosis) are characterized by a localized, tumorous nodule (usually foot) that occurs in response to chronic progressive destruction of skin, subcutaneous tissue, fascia, muscle and bone 

4. Sporotrichosis is caused by the dimorphous fungus, Sporothrix schenckii.
 - traumatic implantation of the fungus growing in soil, thus the association with "rose gardeners disease".
 - MC lymphocutaneous disease → painless nodule at inoculation site → chain of suppurating subcutaneous nodules that drain to the skin surface along the course of the lymphatics.

- cigar shaped yeast forms are seen in the suppurative nodules and asteroid bodies (Splendore-Hoeppi phenomenon) are noted within granulomatous microabscesses.
 - treatment: oral potassium iodide

Multiple myeloma.

Blood picture:

- Marked rouleaux formation.
- Normpcytic normochromic anaemia.
- There may be leucopenia or leucoery!hrohlastic reaction.
- Atypical plasma cells may be seen in some patients
- Raised ESR
- Monoclonal hypergammaglobulinaemia 
- If light chains are produced in excess, they are excreted in urine as bence jones protein

Bone marrow

- Hyper cellular
- Plasma cells from at least 15 – 30% atypical forms and myeloma cells are seen.
 

Osteogenesis Imperfecta (OI) (Brittle bone diseases) 

It is a group of hereditary disorders caused by gene mutations that eventuate in defective synthesis of and thus premature degradation of type I collagen. The fundamental abnormality in all forms of OI is too little bone, resulting in extreme susceptibility to fractures. The bones show marked cortical thinning and attenuation of trabeculae. 

Extraskeletal manifestations also occur because type I collagen is a major component of extracellular matrix in other parts of the body. The classic finding of blue sclerae  is attributable to decreased scleral collagen content; this causes a relative transparency that allows the underlying choroid to be seen. Hearing loss can be related to conduction defects in the middle and inner ear bones, and small misshapen teeth are a result of dentin deficiency 

G-6 PD Deficiency

Occurs in Negroes, Mediterranean races, India and far East. It confers a protection Against falciparum malaria.

It is transmitted as X-linked trait of intermediate dominance (variable effect in homozygous females). 

Haemolysis may be induced by :
•    Primaquin and other anti malarials.
•    Other drugs like chloramphenicol , analgesics, antitubercular drugs etc.
•    Infections.
•    Ingestion of Vicia faba bean (favism).
•    Diabetic acidosis
 

THE THYROID GLAND

The thyroid gland develops embryologically from the developing pharyngeal epithelium that descends from the foramen cecum at the base of the tongue to its normal position in the anterior neck. This pattern of descent explains the occasional presence of ectopic thyroid tissue, most commonly located at the base of the tongue (lingual thyroid) or at other sites abnormally high in the neck. 

Hepatitis A virus.
- Hepatitis A (HAV) is a self-limited hepatitis caused by an RNA virus 

- Symptoms last 2 to 4 weeks.
- There is no risk of developing chronic hepatitis in the future.
- Incubation period is short, lasting 2 to 6 weeks.
- Infection is identified by HAV-specific antibodies (IgM if acute, IgG if past disease).
- The usual route of infection is fecal-oral transmission by contaminated food. There is no carrier state and no chronic disease
- Laboratory diagnosis: ELISA test for IgM antibody.
- Vaccine: killed virus.
- Prevention: serum immunoglobulins are available.