Lung
Infectious
Parasitic
Other parasites
Author: Elliot Weisenberg, M.D.
Last author update: 1 September 2011
Last staff update: 26 March 2021
Copyright: 2003-2025, PathologyOutlines.com, Inc.
PubMed search: cryptosporidium pulmonary, Dirofilaria immitis [title] pulmonary, echinococcal [title] cyst pulmonary, tropical pulmonary eosinophilia [title], Paragonimus kellicotti, Toxoplasma gondii [title] pulmonary
Cite this page: Weisenberg E. Other parasites. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/lungnontumorotherparasites.html. Accessed January 9th, 2025.
Cryptosporidium
Definition / general
- Waterborne protozoal infection that mostly infects intestinal epithelium causing diarrhea or malabsorption
- Often causes self limited illness in immunocompetent patients
- In HIV / AIDS, may spread to hepatobiliary tree or airways
Treatment
- Highly active antiretroviral therapy / HAART, paromomycin and azithromycin may be useful (Int J STD AIDS 2005;16:515)
Microscopic (histologic) description
- Characteristic spores on luminal epithelial cells
- Mucosa with mild lymphocytic infiltrate
Cytology images
Images hosted on other servers:
Cryptosporidium in sputum
Dirofilaria
Clinical features
- Dog heartworm; may infect humans as secondary end stage host, particularly in southern coastal states in US
- Adult worms die in right ventricle, embolize in pulmonary arterial circulation
- Embolization of dead worms may be clinically silent or cause chest pain, fever, chills, hemoptysis or blood eosinophilia
- Evokes necrotizing granulomatous response with vasculitis in lung tissue
- Rarely see dead worms
- Usually self limited in humans but may cause lung infarct
- Usually diagnosed after resection of a nodule to exclude malignancy
- Chest Xray: solitary peripheral pulmonary nodule or coin lesion (Int J Immunopathol Pharmacol 2010;23:345)
Case reports
- 15 year old girl with solitary pulmonary nodule (Arch Pathol Lab Med 2002;126:227)
Microscopic (histologic) description
- Rounded infarct with coagulative necrosis, well demarcated from surrounding normal lung by epithelioid histiocytes and fibrous connective tissue
- Focal calcifications and lymphoid aggregates
- Necrotic nematode has homogenous cuticle without external ridges
- Longitudinal muscle layer just internal to cuticle and internal cuticular ridges
Microscopic (histologic) images
Contributed by Dr. Vladimir Zaitsev
Pulmonary embolization
Pulmonary embolization
Echinococcus
Clinical features
- Also called hydatid cyst
- Humans become infected by eating food contaminated with tapeworm eggs, becoming intermediate hosts
- Eggs from dog tapeworm Echinococcus granulosus or E. multilocularis where foxes are the most common definitive hosts; other species rarely cause hydatid diseae in humans
- For E. granulosus, sheep are most important intermediate hosts; for E. multilocularis, rodents are most important intermediate hosts
- E. granulosus is more common in humans and is most common cestode infection of the lung
- Eggs hatch in duodenum and spread to liver, lung, bone or elsewhere
- E. granulosus cysts are most common in liver, 5 - 15% occur in lung; pulmonary disease is often secondary to hepatic disease (World J Surg 2001;25:46)
- Larvae lodge in capillaries and incite a mononuclear and eosinophilic inflammatory cell response
- Many larvae die, some encyst
- Pulmonary cysts may be asymptomatic or cause respiratory compromise by compressing airways or lung parenchyma; rarely complicated by Aspergilloma (Br J Radiol 2008;81:e279)
- Cyst rupture may cause fatal anaphylactic shock or pneumonia with consequent development of numerous new cysts throughout lung
Case reports
- 52 year old woman with solid nodule resembling malignancy (Cytojournal 2012;9:13)
Microscopic (histologic) description
- Cysts gradually enlarge and years later may be several centimeters in diameter
- Cyst is bilayered and surrounded by fibroblasts, mononuclear cells, eosinophils, multinucleated giant cells
- Daughter cysts usually develop in large mother cyst
- Daughter cysts develop as projections from a germinative layer and form brood capsules
- Degenerating scolices of developing worms produce sediment so called "hydatid sand"
Microscopic (histologic) images
Contributed by Hanni Gulwani, M.B.B.S.
Various images
Cytology images
Images hosted on other servers:
2 cm lung nodule
BAL fluid - scolices
Filaria
Definition / general
- Due to microfilaria of Wuchereria bancrofti or Brugia malayi, which circulate in pulmonary capillaries and cause an immediate type of eosinophilic hypersensitivity reaction
- Patients have high levels of IgE and high titers of filarial antibodies
- Adult worms not seen in lungs
- Restricted to tropical regions
- Tropical eosinophilia may occur from filaria in lymph nodes or spleen (Meyers-Kouwenaar syndrome)
- Symptoms and signs: cough, typically nocturnal, dypsnea, chest tightness, wheezing, fevers, weight loss and eosinophilia
Microscopic (histologic) description
- Rare microfilaria within pulmonary capillaries with marked eosinophilic infiltrate
- Eosinophilic abscesses develop into granulomata
Paragonimus
Clinical features
- Freshwater trematode (lung fluke) found in North America that infects crayfish and crabs as intermediate hosts (MMWR Morb Mortal Wkly Rep 2010;59:1573)
- Humans acquire infection by ingesting raw or undercooked infected shellfish; rarely contaminated seaweed or watercress
- Larvae mature in gut and migrate through diaphragm to infect lungs
- Most cases in Asia due to P. westermani; schistosomiasis may also involve the lung
- May mimic lung tumor (Korean J Parasitol 2011;49:69)
- May require serology to confirm diagnosis
Case reports
- 35 year old man with recurrent pneumothorax and cavitary lesion (Am J Surg Pathol 2003;27:1157)
Microscopic (histologic) description
- Necrotizing or non-necrotizing granulomas with giant cells containing eggs with operculum; also organizing pneumonia (Am J Surg Pathol 2011;35:707)
- Variable vasculitis and pleuritis; also lymphocytes, plasma cells, eosinophils
- Egg is birefringent
Cytology images
Images hosted on other servers:
Paragonimus egg
Paragonimus
ova found in
bronchoalveolar
lavage fluid
Toxoplasma
Definition / general
- Associated with AIDS, immunosuppression including therapy and hematologic malignancy
- May be transmitted in utero
- Ubiquitous intracellular coccidian parasite that causes focal parenchymal necrosis, diffuse interstitial pneumonia
- Cats are definitive hosts, humans are intermediate
- Very high prevalence in France; in US, from 3% to 20% depending on geography, ethnic group
- Humans acquire transmission from ingestion of material contaminated with cat feces or cysts contained in undercooked meat (pork, beef, mutton); infection may be acquired in utero
- Most disease in CNS, eye and heart; pulmonary involvement is in 70% of disseminated cases
- Pulmonary involvement is indicative of disseminated disease and risk of death from CNS disease or bronchopneumonia
- May cause severe morbidity or death in affected neonates
Gross description
- Lungs heavily congested, combined weight approximately 2000 grams
Microscopic (histologic) description
- Organisms present in histiocytes, alveolar lining cells, endothelial cells and pseudocytes abundant in necrotic areas
Positive stains
