Acne vulgaris is a chronic inflammatory disorder usually present in the late teenage years characterized by comedones, papules, nodules, and cysts.
 - subdivided into obstructive type with closed comedones (whiteheads) and open comedones (blackheads) and the inflammatory type consisting of papules, pustules, nodules, cysts and scars.
 - pathogenesis of inflammatory acne relates to blockage of the hair follicle with keratin and sebaceous secretions, which are acted upon by Propionibacterium acnes (anaerobe) that causes the release of irritating fatty acids resulting in an inflammatory response.
 - pathogenesis of the obstructive type (comedones) is related to plugging of the outlet of a hair follicle by keratin debris.
 - chocolate, shellfish, nuts iodized salt do not aggravate acne.
 - obstructive type is best treated with benzoyl peroxide and triretnoin (vitamin A acid)
 - treatment of inflammatory type is the above plus antibiotics (topical and/or systemic; erythromycin, tetracycline, clindamycin).

Congenital heart defect
Congenital heart defects can be broadly categorised into two groups,
o    acyanotic heart defects ('pink' babies) :

 An acyanotic heart defect is any heart defect of a group of structural congenital heart defects,  approximately 75% of all congenital heart defects.
 It can be subdivided into two groups depending on whether there is shunting of the blood from the left vasculature to the right (left to right shunt) or no shunting at all.

Left to right shunting heart defects include 
- ventricular septal defect or VSD (30% of all congenital heart defects),
- persistent ductus arteriosus or PDA, 
- atrial septal defect or ASD, 
- atrioventricular septal defect or AVSD.

Acyanotic heart defects without shunting include 
- pulmonary stenosis, a narrowing of the pulmonary valve, 
- aortic stenosis 
- coarctation of the aorta.

cyanotic heart defects ('blue' babies). 
obstructive heart defects

 cyanotic heart defect is a group-type of congenital heart defect. These defects account for about 25% of all congenital heart defects. The patient appears blue, or cyanotic, due to deoxygenated blood in the systemic circulation. This occurs due to either a right to left or a bidirectional shunt, allowing significant proportions of the blood to bypass the pulmonary vascular bed; or lack of normal shunting, preventing oxygenated blood from exiting the cardiac-pulmonary system (as with transposition of the great arteries).

Defects in this group include 
hypoplastic left heart syndrome,
tetralogy of Fallot, 
transposition of the great arteries, 
tricuspid atresia, 
pulmonary atresia, 
persistent truncus arteriosus.
 

Erythema nodosum is the MCC of inflammation of subcutaneous fat (panniculitis).
 - it may be associated with tuberculosis, leprosy, certain drugs (sulfonamides), and is commonly a harbinger of coccidioidomycosis and sarcoidosis.
 - commonly presents on the lower extremities with exquisitely tender, raised erythematous plaques and nodules.
 - self-limited disease.

Hyperparathyroidism 

Abnormally high levels of parathyroid hormone (PTH) cause hypercalcemia. This can result from either primary or secondary causes. Primary hyperparathyroidism is caused usually by a parathyroid adenoma, which is associated with autonomous PTH secretion. Secondary  hyperparathyroidism, on the other hand, can occur in the setting of chronic renal failure. In either situation, the presence of excessive amounts of this hormone leads to significant skeletal changes related to a persistently exuberant osteoclast activity that is associated with increased bone resorption and calcium mobilization. The entire skeleton is affected. PTH is directly responsible for the bone changes seen in primary hyperparathyroidism, but in secondary hyperparathyroidism additional influences also contribute. In chronic renal failure there is inadequate 1,25- (OH)2-D synthesis that ultimately affects gastrointestinal calcium absorption. The hyperphosphatemia of renal
failure also suppresses renal α1-hydroxylase, which further impair vitamin D synthesis; all these eventuate in hypocalcemia, which stimulates excessive secretion of PTH by the parathyroid glands, & hence elevation in PTH serum levels. 

Gross features
• There is increased osteoclastic activity, with bone resorption. Cortical and trabecular bone are lost and replaced by loose connective tissue. 
• Bone resorption is especially pronounced in the subperiosteal regions and produces characteristic radiographic changes, best seen along the radial aspect of the middle phalanges of the second and third fingers.

Microscopical features

• There is increased numbers of osteoclasts and accompanying erosion of bone surfaces.
• The marrow space contains increased amounts of loose fibrovascular tissue.
• Hemosiderin deposits are present, reflecting episodes of hemorrhage resulting from microfractures of the weakened bone.
• In some instances, collections of osteoclasts, reactive giant cells, and hemorrhagic debris form a distinct mass, termed "brown tumor of hyperparathyroidism". Cystic change is common in such lesions (hence the name osteitis fibrosa cystica). Patients with hyperparathyroidism have reduced bone mass, and hence are increasingly susceptible to fractures and bone deformities.

INFARCTION

Definition : a localized area of ischaemic necrosis in an organ infarcts may be:
Pale :as in
    →    Arterial obstruction.
    →    solid organs.
Red as in
    →    Venous occlusion
    →    Loose tissue.

Morphology
Gross: infarcts are usually wedge shaped the apex towards the occluded vessel They are
separated from the surrounding tissue by an hyperemic inflammatory zone

Microscopic:
- An area of coagulative necrosis with a rim of congested vessels and acute inflammatory infiltration of the tissue .
- The polymorphs ale later replaced by mononuclear cells and granulation tissue.
- With time, scar tissue replaces necrosed tissue.
 

Infections caused by gonorrhea

1.  Acute urethritis.  Mostly in males.  Generally self-limiting.  Dysuria and purulent discharge.

2.  Endocervical infection.  Purulent vaginal discharge, abnormal menses, pelvic pain.  Often co-infection with other STD’s.  Some women are asymptomatic.

3.  Pelvic Inflammatory Disease (PID).  Consequence of ascending endocervical infection.  Causes salpingitis, endometriosis, bilateral abdominal pain, discharge, fever.  May lead to sterility, chronic pain, and ectopic pregnancy because of loss of fallopian cilia.

4.  Anorectal inflammation.  Mostly in homosexual men.  Pain, itching, discharge from anus.

5.  Dermatitis/arthritis.  Occurs after bacteremia.  Skin will have papules on an erythematous base which develop into necrotic pustules.  Asymmetric joint pain.  These infections are susceptible to penicillin.

6.  Neonatal infections.  Ophthalmia neonatorum is a conjunctival infection from going through infected vagina.  After one year of age, suspect child abuse.