Diagnosis: Paragonimiasis.
Eggs of Paragonimus species (Figure 3) were found in the fifth sputum sample processed and examined for ova and parasites as well as in a stool sample. A biopsy of the skin nodule exhibited fibroadipose vascularized tissue surrounding a cavity covered by granulation tissue with acute and chronic inflammation and palisading histiocytes tending to form granulomas.
Chest computed tomography scan showing a nodule on the mid-lower area of the left lung parenchyma (arrow).
Migratory subcutaneous nodule under the patient's right breast (arrow).
Sputum sample processed for ova and parasites showing a Paragonimus species egg. This finding is related to the rupture of a pulmonary cystic lesion containing a mature fluke into the bronchiole lumen. The egg is characterized by its oval or elongated shape (range, 80–120 µm long by 40–70 µm wide); brown-yellow content; and thick shell that is thicker at the abopercular end (arrow), with an operculum at the opposite end (arrowhead).
There was a moderate eosinophilic infiltrate and the acid-fast stain was negative.
On further questioning, the patient recalled that about a year before the onset of symptoms, she was feeling weak and tired with back pain and thought she had cancer. Friends and relatives advised her to eat crayfish from the local rivers, and she started eating crayfish cebiche, a typical Peruvian dish made with uncooked seafood, about 1 year before.
Paragonimiasis is a lung fluke infection acquired by the consumption of raw or undercooked crab. More than 50 species of Paragonimus have been described, approximately 16 causing disease in humans. Paragonimus westermani is endemic to Southeast Asia, followed by Paragonimus skrjabini and Paragonimus miyazakii, whereas Paragonimus africanus and Paragonimus uterobilateralis cause infection in Africa, and Paragonimus mexicanus is distributed along Central and South America. Although rare, Paragonimus kellicotti has been shown to cause infection in the United States [1].
Infectious metacercariae penetrate the duodenum and travel to the lung parenchyma where they mature encapsulated in cystic pockets, often living up to 20 years [2, 3]. Clinically, in the first 2 months following infection or at the acute phase, patients are asymptomatic or may present symptoms related to the larval migration period within the peritoneal and pleuritic cavities: fever, malaise, diarrhea, epigastric pain, urticaria, pleuritic pain, dyspnea, and cough. During the chronic phase of the infection, when mature flukes inhabit the lungs, patients commonly present with recurrent hemoptysis, as our patient did. The sputum has a rusty brown color and contains eggs whenever the capsule surrounding a mature fluke breaks into a bronchiole. Eosinophilia is often present [4, 5].
Even though extrapulmonary disease is relatively uncommon, the preferred infection sites are the central nervous system, abdominal cavity, and subcutaneous tissue. Subcutaneous disease manifests as painless migratory nodules containing immature flukes, usually on the lower abdominal wall, inguinal area, and proximal lower extremities (Figure 2) [5, 6]. The frequency of subcutaneous nodules varies from 20% to 55.8%, and seems to depend on the species [1, 7, 8]. Nodules can be single or multiple at the same time. Even when these nodules are caused by the migration of immature flukes, the worm is usually not present in the biopsy, and nonspecific findings related to an inflammatory response are described, including eosinophilic infiltrates [9].
Typically, on chest radiograph one can identify focal or segmental airspace consolidations, cystic lesions, linear opacities on the lungs, or pleural effusions [10]. The most frequent computed tomographic finding is a poorly marginated subpleural or subfissural nodule of 2 cm in diameter containing a low-attenuation area, associated with pleural thickening (Figure 1) [11]. These lesions are commonly found in the mid-lower lung zones [4, 12].
The diagnosis of tuberculosis was reconsidered in this patient due to the failure to respond to treatment, the presence of high eosinophilia, a rare finding in tuberculosis, and the location of the nodular lesions on the lower lung fields as opposed to upper lung fields in tuberculosis. The patient was treated with praziquantel, and within days her respiratory symptoms and hemoptysis improved, as did the eosinophilia, without side effects or complications.
Note
Potential conflicts of interest. All authors: No potential conflicts.
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