NEET MDS Lessons
General Pathology
ADRENOCORTICAL TUMORS
Functional adenomas are commonly associated with hyperaldosteronism and with Cushing syndrome, whereas a virilizing neoplasm is more likely to be a carcinoma. Determination of of the functional status of a tumor is based on clinical evaluation and measurement of the hormone or its metabolites. In other words, functional and nonfunctional adrenocortical neoplasms cannot be distinguished on the basis of morphologic features.
Patholgical features
Adrenocortical adenomas
- They are generally small, 1 to 2 cm in diameter.
- On cut surface, adenomas are usually yellow to yellow-brown due to presence of lipid within the neoplastic cells
- Microscopically, adenomas are composed of cells similar to those populating the normal adrenal cortex. The nuclei tend to be small, although some degree of pleomorphism may be encountered even in benign lesions ("endocrine atypia"). The cytoplasm ranges from eosinophilic to vacuolated, depending on their lipid content.
Adrenocortical carcinomas
These are rare and may occur at any age, including in childhood.
- Carcinomas are generally large, invasive lesions.
- The cut surface is typically variegated and poorly demarcated with areas of necrosis, hemorrhage, and cystic change.
- Microscopically, they are composed of well-differentiated cells resembling those of cortical adenomas or bizarre, pleomorphic cells, which may be difficult to distinguish from those of an undifferentiated carcinoma metastatic to the adrenal.
Agranulocytosis. Severe neutropenia with symptoms of infective lesions.
Drugs. are an important cause and the effect may be due to .
-Direct toxic effect.
-Hypersensitivity.
Some of the 'high risk drugs are.
-Amidopyrine.
-Antithyroid drugs.
-Chlorpromazine, mapazine.
-Antimetabolites and other drugs causing pancytopenia.
Bloodpicture: Neutropenia with toxic granules in neutrophils. Marrow shows decrease in granulocyte precursors with toxic granules in them.
Staphylococcal aureus
- cutaneous infections
- furuncles (boils)
- carbuncles (more complicated furuncle with multiple sinuses)
- impetigo (often mixed with Streptococcus and has a more bullous appearance than crusted)
- hidradenitis suppurative (abscess of apocrine glands→e.g., axilla)
- nail bed (paronychial infection)
- postoperative wound or stitch abscess
- postpartum breast abscesses
toxin related skin rashes
- infants and young children develop toxic epidermal necrolysis or Ritter's syndrome (scalded baby syndrome)→large, red areas of denuded skin and generalized bulla formation.
- toxic shock syndrome (TSS) is due to a toxin producing strain of Staphylococcus aureus (bacteriophage induced) usually, but not exclusively in tampon wearing (hyperabsorbent type), menstruating women; 1-4 day prodrome of high fever, myalgias, arthralgias, mental confusion, diarrhea and on erythematous rash that occurs during or soon after menses; rash predominantly on hands and feet with eventual desquamation in 5-12 days.
CHRONIC INFLAMMATlON
When the inflammatory reaction instead of subsiding after the acute phase (or without entering an acute phase), persists as a smouldering lesion, it is called chronic inflammation. .
Characteristics
- Predominantly mononuclear response.
- Inflamation.and..repair going on simultaneously.
- Usually results in more prominent-scarring.
Causes:
Chronicity may be due to :
- Defective defence mechanisms.
- Persistence of injurious agent.
(a) Certain organisms resist phagocytosis and destruction e.g tubercle bacillus, fungi
(b) insoluble particulate matter e.g., crystals. fibres suture materials.
(c) Constants supply of causative agent as in autoimmune disease where body reacts against its own tissues.
- Defective healing.
Granulomatous inflammation
It is a type of chronic inflammation characterised by localised collections of histiocytes.
These cells are usually accompanied by lymphocytes, fibroblasts and giant cells also.
Granulomas are characteristically seen in diseases like tuberculosis. syphilis, leprosy, sarcoidosis, fungal infections etc. In some of these, the lesion is morphologically distinct enough to point to the type of underlying disease. These are sometimes called' specific' granulomas. Granulomas can also be elicited by particulate, insoluble foreign material e.g. granuloma, suture granuloma, cholesterol granuloma (organising haemorrhages).
Parathyroid hormone
Parathyroid hormone (PTH) is a polypeptide (84 amino acid residues) secreted by the chief cells of the parathyroid glands (four glands: two in each of the superior and inferior lobes of the thyroid; total weight 120 mg).
The main action of PTH is to increase serum calcium and decrease serum phosphate.
Its actions are mediated by the bones and kidneys -
In bone, PTH stimulates osteoclastic bone resorption and inhibits osteoblastic bone deposition. The net effect is the release of calcium from bone.
In the kidney, PTH has the following effects:
- Increases calcium reabsorption.
- Decreases phosphate reabsorption.
- Increases 1-hydroxylation of 25-hydroxyvitamin D (i.e. activates vitamin D).
PTH also increases gastrointestinal calcium absorption.
Parkinson’s disease
a. Characterized by the degeneration of neurons in the basal ganglia, specifically the substantia nigra and striatum.
b. Histologic findings in affected neurons include Lewy bodies.
c. Clinically, the disease affects involuntary and voluntary movements. Tremors are common. Symptoms include pin-rolling tremors, slowness of movements, muscular rigidity, and shuffling gait.
Actinic keratosis
1. Dry, scaly plaques with an erythematous base.
2. Similar to actinic cheilosis, which occurs along the vermilion border of the lower lip.
3. Caused by sun damage to the skin.
4. Dysplastic lesion, may be premalignant.