Histoplasmosis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Prince Tano Djan, BSc, MBChB [2], Aravind Kuchkuntla, M.B.B.S[3]

Overview

Patients with acute and chronic pulmonary histoplasmosis present with features similar to pneumonia. Therefore it must be differentiated from conditions presenting with cough, fever and dyspnea such as tuberculosis, sarcoidosis and other fungal infections.

Differentiating Histoplasmosis from other Diseases

The following table is a list of diseases presenting with similar features of histoplasmosis such as cough and fever:

Pathogen	Disease	Geographic distribution	High risk Groups	Differentiating features		Microscopic findings
				Physical exam	Laboratory findings
Fungal	Histoplasmosis	Mississippi and Ohio River valleys	Cave dwellers Soil that contains bird or bat dropping	Palate and oral ulcers Splenomegaly	Pancytopenia Urine antigen testing	Yeast are typically smaller, with narrow-based budding, found intracellularly within macrophages
	Coccidioidomycosis	Southwestern US region	Opportunistic infection seen in AIDS	Rash on upper body or legs Night sweats	Serologic tests( enzyme immune assay )more sensitive	Characteristic spherule appearance
	Paracoccidioidomycosis	Central and South america	Opportunistic infection seen in AIDS	Lymphadenopathy Hepatosplenomegaly Bone marrow dysfunction	Elevated liver enzymes Hyperbilirubinemia Hypoalbuminemia	Smaller fungi with thin cell walls, forming mariner wheel appearance, circumferentially surrounding the parent cell.( Captain wheel appearance )
	Sporotrichosis	Ubiquitous	Gardeners	Extremities Lymphadenitis (nodular)	+ Sporotrichin skin test	Finger or cigar shaped yeast.
	Aspergillosis	Ubiquitous	Cystic fibrosis or asthma. tuberculosis. Immunocompromised	Wheezing Stuffiness, runny nose Hemoptysis Weight loss	Cell wall detection using galactomannan antigen detection, Beta-D-glucan detection test.	Septated hyphae with acute angle branching
Bacterial	Anthrax	Ubiquitous	Live stock handlers	Painless skin ulcer with a black center  Bloody diarrhea	Thrombocytopenia Hyponatremia ↑ BUN Hypoalbuminemia ↑ Troponin.	Nonmotile, Gram-positive, aerobic or facultatively anaerobic, endospore-forming, rod-shaped bacterium
	Legionella	Ubiquitous	Chronic lung disease Building water systems	Diarrhea Confusion	+ Urine Antigen Hyponatremia	Gram negative bacterium
	Tuberculosis	Asia,Africa	Ill contact individuals	Night sweats Hemoptysis	Hypercalcemia Elevated alkaline phosphatase levels fluorescence microscopy (auramine-rhodamine staining)+ for baccilli.	Aerobic, non-encapsulated, non-motile, acid-fast bacillus
	Listeriosis	Ubiquitous	Pregnant women Adults > 65 Immunocompromised.	Pregnancy can lead to miscarriage, stillbirth, premature delivery, Non-pregnant : headache, stiff neck, confusion, loss of balance, and convulsions	Elevated titers of listeriolysin O CSF analysis :Pleocytosis lymphocytes  ↑CSF protein   ↓ CSF glucose	flagellated, catalase-positive, facultative intracellular, anaerobic, nonsporulating, Gram-positive bacillus
	Brucellosis	Mexico, South and Central America	People who take unpasteurized dairy products	Arthritis Testicular and scrotal swelling Endocarditis	Antibody production against lipopolysaccharide and bacterial antigens Relative lymphocytosis and thrombocytopenia.	Gram-negative bacteria,non-motile, encapsulated coccobacilli.
	Scrub typhus	Asia-Pacific region Australia Afghanistan	Hikers	Maculopapular rash	Indirect immunofluorescence + Weil-Felix test	a Gram-negative α-proteobacterium  intracellular parasite
	Leptospirosis	Temperate, tropical climates.	People who work with animals	Jaundice Red eyes Kidney failure	Antibodies labelled with fluorescent markers positive for leptospires. Microscopic agglutination test +	Spiral-shaped bacteria with hooked ends on dark-field.
	Cat scratch fever	Ubiquitous	cat licking a person's open wound, or bites or scratches a person	Lymphadenopathy Papule or pustule at the infected site	enzymatic immunoassay positive for antibody to B henselae lymphocytosis	Gram-negative bacteria. facultative intracellular parasites
Viral	Chickenpox	−	Pregnant women. Infants born at less than 28 weeks gestation Immunocompromised persons	conjunctival and catarrhal symptoms Spots appearing in two or three waves	Whole infected cell (wc) ELISA for IgG.	−
	Coxsackie A virus	−	Children attending day care	Painful blisters in the mouth, palms and on the feet. Rash, appears after episode of high fever.	Clinically diagnosed	−
Others	Primary lung cancer	−	Age >65	Weight loss H/o smoking Hemoptysis	CT guided bronchoscopy + for malignant cells	−