Sandbox:Preeti

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Preeti Singh, M.B.B.S.[2]

			Pathophysiology	Symptoms	Laboratory Findings
					Immunochemistry	Blood work	Biospy/CT/CXR
Infections	Bacterial	Syphilis	Syphilis is caused by a spirochete, Treponema pallidum. It has an average incubation period of 3 - 12 weeks. Spirochete penetrates intact mucous membrane or microscopic dermal abrasions and rapidly enters systemic circulation with the central nervous system being invaded during the early phase of infection. The histopathological hallmark findings are endarteritis and plasma cell-rich infiltrates reflecting a delayed-type of hypersensitivity reaction to the spirochete.	Primary syphilis Mononuclear leukocytic infiltration, macrophages, and lymphocytes Swelling and proliferation of small blood vessels Secondary syphilis Swelling and dilatation of blood vessels in the dermis Epidermal hyperplasia and neutrophilic infiltration Inflammatory cell infiltrate, predominantly plasma cell Tertiary syphilis Small vessel inflammation (endarteritis obliterans) Granulomatous lesions (gumma) containing central necrosis, inflammatory cells, such as lymphocytes, macrophages, plasma cells and fibroblasts.	A presumptive diagnosis of syphilis is possible with the use of two types of serologic tests. Nontreponemal tests (e.g., venereal disease research laboratory (VDRL) and rapid plasma reagent test) and Treponemal tests (e.g., fluorescent treponemal antibody absorbed (FTA-ABS) tests, the T. pallidum passive particle agglutination (TP-PA) assay, various enzyme immunoassays, and chemiluminescence immunoassays).		Darkfield examinations and tests to detect T. pallidum.
		Brucellosis	humans could be infected by eating undercook meat or raw dairy products, inhalation of the bacteria and direct contact of bacteria with skin wounds or mucous membranes. Following transmission, white blood cells phagocyte the pathogen and transports it via hematologic or lymphatic route to different organs specially to those of the reticuloendothelial system.	Fever Rash Abdominal pain weightloss Painful lymphadenopathy hepatosplenomegaly arthritis	Relative lymphocytosis positive titer of anti-brucella antibodies on serological testing There are two types of serological tests, based on: Antibody production against lipopolysaccharide Antibody production against other bacterial antigens		Brucella is most commonly isolated from blood cultures (blood cultures are positive between the 7th and 21st day)
	Viral	infectious mononucleosis	Epstein-Barr virus, frequently referred to as EBV, the virus infects B cells located in the oropharyngeal epithelium and subsequently spreads to involve the lymph nodes, liver and spleen. incubation period ranges from 4 to 6 weeks.	Characteristic triad of fever, pharyngitis, and lymphadenopathy lasting for 1 to 4 weeks. Common symptoms include low-grade fever without chills, sore throat, white patches on tonsils and back of the throat, muscle weakness and sometime extreme fatigue, tender lymphadenopathy, petechial hemorrhage and skin rash.	presence of atypical lymphocytes (often recorded by automated blood analyser machines as an increase in the monocycte count) is characteristic of EBV infection.	Peripheral Blood Smear hallmark of the disease is the presence of atypical lymphocytes (a type of mononuclear cell) . Atypical lymphocytosis is present in approximately 75% of patients Greater than 10% atypical lymphocytes is diagnostic of mononucleosis.
		cytomegalovirus		Common symptoms include sore throat, swollen lymph nodes, fever, headache, fatigue, weakness, muscle pain and loss of appetite. Abdominal examination reveals splenomegaly. Maculopapular rash may be present.	Positive monospot test. Elevated liver enzymes.
		human immunodeficiency virus	Acute HIV infection may be asymptomatic or may cause a mononucleosis-like syndrome	fever, fatigue, sore throat, myalgia, and lymphadenopathy
		cat scratch fever	The causative organism was first thought to be Afipia felis, but this was disproved by immunological studies demonstrating that cat scratch fever patients developed antibodies to two other organisms, Bartonella henselae (B. henselae) and Bartonella clarridgeiae, which are rod-shaped Gram-negative bacteria.
	Mycobacterial	tuberculosis	Mostly in endemic areas	Symptoms include productive cough,night sweats, fever and weight loss	Sputum smear positive for acid-fast bacilliand nucleic acid amplification tests (NAAT) is used on sputum or any sterile fluid for rapid diagnosis and is positive for mycobacteria.		CXR and CT demonstrates cavities in the upper lobe of the lung
	Parasitic	toxoplasmosis	A parasitic disease caused by ingestion of cat feces, affect all organs and particularly dangerous in pregnant woman. Toxoplasma infections may also present with a mononucleosis-like syndrome seen in patients with acute HIV syndrome.
Autoimmune	Systemic lupus erythematosus
	Sjögren's syndrome
	Hydantoin derivatives
	Sarcoidosis		More common in African-American females Often asymptomatic except for enlarged lymph nodes Associated with restrictive lung disease Erythema nodosum Lupus pernio (skin lesions on face resembling lupus) Bell palsy Epithelioid granulomas containing microscopic Schaumann and asteroid bodies				On CXR bilateral adenopathy and coarse reticular opacities are seen. CT of the chest demonstrates extensive hilar and mediastinal adenopathy Additional findings on CT include fibrosis (honeycomb, linear, or associated with bronchial distortion), pleural thickening, and ground-glass opacities. Biopsy of lung shows non-caseatinggranuloma
Neoplasms	Hodgkin's disease		Reed-Sternberg cell B-cell origin CD30 (Ki-1) and CD15 (Leu-M1) antigens	Painless localized peripheral lymphadenopathy B symptoms	Fine-needle aspiration Mononucleate and binucleate Reed-Sternberg cells in a background of inflammatory cells Lactate dehydrogenase (LDH) may be increased. ESR elevated Serum creatinine elevated in nephrotic syndrome. Alkaline phosphatase (ALP) increased Hypercalcemia, hypernatremia, and hypoglycemia.
	Chronic lymphocytic leukemia
	Small cell carcinoma of the lung
	Malignant histiocytosis
	Melanoma
	Germ cell neoplasms
Other conditions	Reactive lymphoid hyperplasia
	Lymphomatoid granulomatosis
	Dermatopathic lymphadenopathy
	Angioimmunoblastic lymphadenopathy
	Giant lymph node hyperplasia (Castleman disease)