Hereditary spherocytosis.

Functionally normal cells which are destroyed .in spleen because of the structural abnormality. It is transmitted as an autosomal dominant trait 

Congenital hemolytic anemia due to genetically determined abnormal spectrin and ankyrin molecules, leading to defects in red blood cell membrane, causing spherical shape and lack of plasticity
Red blood cells become trapped within spleen and have less than usual 120 day lifespan
Splenic function is normal
Osmotic fragility: increased; basis for diagnostic testing 

Description

Firm, deep red tissue, thin capsule, no grossly identifiable malpighian follicles, 100-1000g
Peripheral blood images
Marked congestion in cords
Sinuses appear empty but actually contain ghost red blood cells
May have prominent endothelial lined sinuses, hemosiderin deposition, erythrophagocytosis

Streptococcal pharyngitis:

A disease of young people, enlarged lymphoid nodules and keratin plugs in the tonsillar pits is seen Complications include retro-pharyngeal abscess (quinsy)

Cellulitis of the deep tissues of the neck is Ludwig's angina

Scarlet fever ("scarlatina") is a strep throat caused by a streptococcus with the gene to make one of the erythrogenic toxins, Patients have a rash with PMNs

Streptococcal skin infections (Impetigo)

Erysipelas is a severe skin infection caused by group A strep; geographic of red, thickened, indurated areas of the skin are characteristic. Unlike staph infections, there is usually little or no tissue necrosis

Post-streptococcal hypersensitivity diseases include rheumatic fever, post-streptococcal glomerulonephritis, and some cases of erythema nodosum

Biliary cirrhosis(16%)

It is due diffuse chronic cholestaisis (obstruction of the biliary flow) leading to damage and scarring all over the liver. Two types are known  
1. Primary biliary cirrhosis and
2. Secondary biliary cirrhosis. 

Primary biliary cirrhosis
It is destructive chronic inflammation of intrahepatic bile ductules and small ducts leading to micronodular cirrhosis. 
-Typically affects middle aged women. 
- Patients present with fatigue, pruritis and eventually, jaundice. 

Cause:-  Autoimmune. Patients have autoantibodies directed against mitochondrial enzymes (AMA). 

Pathology:- 

 Liver is enlarged, dark green in color (cholestaisis). Cirrhosis is micronodular. 

M/E :-
- Early, portal tracts show lymphocytes and plasma cell infiltrate the bile ducts and destroy them.
- Granulomatous inflammation surrounding the damaged and inflamed bile ducts is the hallmark of (PBC).
- Cholestatic changes such as bile ductular proliferation, periportal Mallory’s hyaline and increased copper in periportal hepatocytes.
- In the end stage disease, micro nodular cirrhosis occurs and the inflammatory changes subside 

Secondary biliary cirrhosis:-
 It is extra hepatic (surgical) cholestaisis due to prolonged extra hepatic major bile duct obstruction. 

Causes - Obstruction of hepatic or common bile duct by: 
   - Congenital biliary atresia.       
   - Pressure by enlarged LN or tumor   * Biliary stones. 
   - Carcinoma of the bile duct, ampulla of Vater or pancreatic head

Effects of obstruction:- 
Complete obstruction leads to back pressure all over the biliary tract           
 - damage by inspessated bile          
 - inflammation and scarring.
Incomplete obstruction  leads to acute suppurative cholangitis and cholangiolitis. 

Nevus

A nevus refers to any congenital lesion of the skin, while a nevocellular nevus specifically refers to a benign tumor of neural crest-derived cells that include modified melanocytes of various shapes (nevus cells).
 - nevocellular nevi are generally tan to deep brown, uniformly pigmented, small papules with well-defined, rounded borders.
 - most nevocellular nevi are subdivided into junctional, intradermal, or compound types.
 - most nevocellular nevi begin as junctional nevi with nevus cells located along the basal cell layer producing small, flat lesions, which are only slightly raised. 
- junctional nevi usually develop into compound nevi as nevus cells extend into the underlying superficial dermis forming cords and columns of cells (compound: nevi at junction and in the dermis).
 - eventually, the junctional component of a nevocellular nevus is lost, leaving only nevus cells within the dermis, thus the term intradermal nevus.
 - junctional → compound → intradermal nevus.
 - although uncommon, certain nevi may evolve into a malignant melanoma, particularly those which are congenital and those which are referred to as dysplastic nevi.
 - a dysplastic nevus is commonly associated with patients who have multiple scattered nevi over the entire body (dysplastic nevus syndrome) with individual lesions that have a diameter greater than 1 cm.

Salivary gland pathology

Inflammation 

a. Sialolithiasis produces a secondary inflammatory reaction  to obstruction and the resultant enlargement of ducts by stones. It may be complicated by actual infection with mouth flora. 

b. Sialadenitis is a primary inflammatory reaction, but it is not always infectious. It may be part of an autoimmune disease  (e.g., Sjogren's syndrome), or the result of bacterial or virals (e.g., mumps) infection. 

Sjögren’s syndrome

a. An autoimmune disease of the salivary and lacrimal glands.
b. Autonuclear antibodies (ANAs) against salivary ducts may be seen.
c. Triad of symptoms include:
(1) Xerostomia—from decreased saliva production.
(2) Keratoconjunctivitis sicca (dry eyes)—from decreased tear production.
(3) Rheumatoid arthritis.
(4) Enlargement of the salivary or lacrimal glands, known as Mikulicz syndrome, may also be observed. 

d. Histologically, a dense infiltration of the gland by lymphocytes is observed.

Tumors

The parotid gland accounts for more than three-quarters of these tumors, most of which are benign. Of the remainder, more occur in the submandibular gland than in the sublingual, and most of these are malignant. Many are surgically, cured, but local recurrence is common. 

a. Pleomorphic adenoma is generally benign and accounts for approximately three-quarters of all salivary gland tumors. If  is composed of multiple epithelial and mesenchymal cell types. Complications may arise due to involvement of cranial nerve VII. 

(a) The most common salivary gland tumor.
(b) Is benign.
(c) Prognosis is good after proper surgical excision.

b. Warthin's tumor (adenolymphoma) is also benign, occuring almost exclusively in the parotid gland. It is grossly cystic.

Microscopic examination reveals cell types suggestive of branchial cleft origin embedded in a lymphoid matrix. 

c. Mucoepidermoid tumors also occur primarily in the parotid and have a high rate of malignant transformation.The malignant component is usually squamous cell.  Prognosis of tumor depends on grade and stage of disease.

d. Cylindroma (adenoid cysticc. Mucoepidermoid tumors carcinoma) is more common in the minor salivary glands found in the oral mucosa, and metastases are more common than in other tumors of the salivary glands. Facial nerve complications are frequent. 
(1) Grossly, the tumor forms multiple lobules surrounded by a capsule. 
(2) Microscopically, small cells form glands containin mucoid material 

Lupus erythematosus
 - chronic discoid lupus is primarily limited to the skin, while SLE can involve the skin and other systems.
 - pathogenesis: light and other external agents plus deposition of DNA (planted antigen) and immune complexes in the basement membrane.
 Histology:
 - basal cells along the dermal-epidermal junction and hair shafts (reason for alopecia) are vacuolated (liquefactive degeneration)
 - thickening of lamina densa as a reaction to injury.
 - immunofluorescent studies reveal a band of immunofluorescence (band test) in involved skin of chronic discoid lupus or involved/uninvolved skin of SLE.
 - lymphocytic infiltrate at the dermal-epidermal junction and papillary dermis.