domingo, 28 de junio de 2015

A 40-Year-OldWoman From a Native Indian CommunityWith Non- Hodgkin Lymphoma and Hemoptysis - ANSWER

Figure 1. High-resolution computed tomography scan showing a thinwalled cavity in the left superior lobe with a focal consolidation (arrow).

Figure 2. Ovoid-shaped egg of Paragonimus species, with a thick shell, with one end slightly flattened. At the large end, the operculum is clearly visible (arrow), and the opposite (abopercular) end is thickened. The eggs
are unembryonated when passed in sputum.

Diagnosis: pulmonary paragonimiasis.

The computed tomographic findings show a thin-walled cavity in the left superior lobe with a focal consolidation (Figure 1). A bronchoscopy was performed to rule out any involvement by opportunistic pathogens or neoplastic infiltration and to define treatment before the beginning of chemotherapy.

The direct evaluation of bronchoalveolar lavage fluid showed the presence of yellowish brown eggs, thick-shelled with an obvious operculum, characteristic of Paragonimus species (Figure 2). Based on the egg morphology, ovoid shape, eggshell and operculum, and epidemiology, the most likely species infecting this patient was Paragonimus mexicanus. Serological tests were not performed because they are not available in our country. The patient was treated with praziquantel 600 mg every 8 hours for 48 hours with resolution of the symptoms. Then the patient received R-CHOP (Rituximab - Cyclophosphamide, Hydroxydaunorubicin, Oncovin [vincristine], Prednisone) chemotherapy with significant reduction of the tumoral mass and at present is still receiving chemotherapy without infectious complications.

Paragonimiasis is a foodborne anthropozoonotic disease caused by the trematode Paragonimus species. Human infections have been reported in 39 countries, with 9 species identified that cause infections in humans. Paragonimus westermani is the most important and widely distributed of the many Paragonimus species that exist, and is frequently encountered in Southeast Asia and China, whereas P. kellicotti has been reported in North America. This is an expected condition in endemic tropical and subtropical countries of the Americas. In South America, paragonimiasis has been reported from Mexico to Brazil, and the species have been named according to the country where they have been identified, hence their names: P. mexicanus (Mexico), P. peruvianus (Peru), P. ecuadoriensis (Ecuador). In our country 5 endemic foci have been identified in the Embera Indian communities located on the Colombian Pacific coast.
Unfortunately, this population rarely seeks medical care and therefore the incidence of the disease is hard to establish and is underestimated. Even though the species Paragonimus caliensis has been identified in animals, and there are some studies in humans in our area, the species of Paragonimus has not been determined so the predominant species is unknown.

The infection in humans, an accidental host, occurs as a result of the ingestion of raw freshwater crabs, crayfish, and other crustaceans infected with the metacercariae. After the ingestion, the metacercariae hatch in the intestine and young worms penetrate the intestinal wall and the peritoneum, then the diaphragm and the pleura; finally reaching the lungs, where they produce the typical symptoms of the disease. A more unusual and atypical presentation results from ectopic involvement that results from erratic migration of the juvenile worms, with locations in the abdominal cavity, subcutaneous tissues, and brain.
Many patients with pulmonary P. westermani infections may have nonspecific signs and symptoms, usually with radiologic abnormalities such as lung infiltrates, nodules and cavities, airspace consolidation, or pleural effusions that may mimic tuberculosis. The diagnosis is made by direct visualization of the eggs in the sputum or bronchoalveolar lavage fluid; although the sensitivity of this test is low (30%–40%), repeated sputum examinations may increase the yield (54%–89%). The sensitivity of a stool examination is inferior to that of a sputum examination, with the sensitivity of a single stool examination being in the range of 11%–15%; examination of 3 stool specimens raises the sensitivity to 25%. Based on the egg morphology, in some instances, the species identification is possible.
For example, the eggs of P. kellicotti are bigger than those of P. mexicanus (average, 91.22 ± 3.60 μm in length with a mean width of 56.70 ± 1.78 μm vs 74.11 ± 3.28 μm in length with a mean width of 44.45 ± 1.97 μm, respectively), and the eggshells of P. kellicotti are thicker than those of P. mexicanus (average, 2.27 ± 0.26 μm vs 1.17 ± 0.19 μm, respectively). These features are important for differentiating P. mexicanus from P. kellicotti, both of which have a similar egg shape (broadest centrally) that is distinctly different from that of P. westermani, which is broadest near the operculum and has more distinct abopercular thickening.

Another tool especially useful regarding the extrapulmonary forms of the disease, in which diagnosis and isolation of the parasite is more difficult, is serological testing that allows the species to be differentiated; for example, enzyme-linked immunosorbent assay is highly sensitive (96%) and specific (99%) for P. westermani.

In general, paragonimiasis has a good prognosis and excellent clinical response to treatment if the diagnosis is made promptly. In our region, more public health interventions are needed to allow early detection and treatment of the population at risk.

Clinical Infectious Diseases 2013;57(5):765–6

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