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PULMONARY FILARIOSIS: A CASE REPORT M. Costa Angeli, E. Cassina,C. Arrigoni, E. Tisi, D. Ballabio, E. Corno, T.Di Sibio, *M. Cereda, **G. Bovo, **A. Brenna, C. Benenti. Divisione di Chirurgia Toracica,* Servizio di Anestesia e Rianimazione, Servizio di Anatomia Patologica – Ospedale San Gerardo – Azienda Ospedaliera - Monza
We
describe a case of pulmonary filariosis
that we observed in December 1997. A
36 year old man, reporting chest pain, was referred to our department from
another hospital, where a left pulmonary effusion was detected.
We performed the following studies: · Fiberoptic bronchoscopy: no abnormal finding; · B.A.L.: alveolar macrophages, granulocytes, pavement cells, cylindrical cells, no neoplastic cells; · Pulmonary function tests: mild obstructive-disventilatory syndrome involving especially the proxymal airways; · Chest CT scan: 3 cm wide left lower lobe peripheral mass with bronchogram; · Abdominal echo-scan: no abnormal finding; · Chest X-ray: 2 cm lingular consolidation, with associated pleural effusion; · Bone nuclear scan: increased captation in the posterior part of the 3rd and 5th rib; · Left ribs X-ray: no bone lesions. Left lower peripheral consolidation;
·
CBC: moderate eosinophilia.
On December 16th 1997 the patient underwent VATS surgery. We identified a
target-shape inflammatory lesion, involving the left lower lobe at the level of
the scissure. An atypical segmentectomy was performed.
The
histology identified areas of inflammation and necrosis with no neoplastic
findings. The final histology showed a pulmonary nodule with infarcted tissue,
surrounded by a fibro-histiocytary granulomatous wall, with few eosinophils, and
with widespread plasmacellular arteritis. The lesion showed also “cellular
shades” and a nematode within an arterial vessel. The nematode, which had wide
cuticule, thick muscle layer, double uterus, and small gut, was classified as a
female of Dirofilaria, probably a Dirofilaria Immitis.
The
post-operative course was normal, except an increase in eosinophilia from 4.8%
to 10.9%. The patient was discharged in good conditions.
Pulmonary
filariosis is a rare disease. 87 cases have been reported in the U.S and 2 in
Italy, so far. It is transmitted from dogs to humans through infected mosquitoes.
Its usual manifestation is a solitary, spherical nodule, of 1 to 3 cm of
diameter. The finding is mostly occasional, by routine chest X-ray. Patiens are
usually asymptomatic; sometimes cough, hemoptysis, or chest pain are reported.
Histologically, the lesion is delimited, with a central necrotic area surrounded
by a granullomatous area. The latter is surrounded by a fibrotic wall. The
parasyte, which is often detected within a small artery, usually lives in the
subcutaneous tissues but occasionally can migrate into the right ventricle and
from here to the pulmonary circulation, after its death. The resulting
infarctual lesion is self-limited and is not life-threatening to the host. This
totally benign disease is interesting, because it can be confused with a primary
or methastatic lung cancer. Thoracotomy and lung excisional biopsy are therefore
necessary to confirm diagnosis. Surgeons and pathologists should keep into
account that the incidence of pulmonary filariosis is increasing, when
evaluating the etiology of pulmonary granulomatous lesions.
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