Pulmonary dirofilariasis: a clinicopathologic study of 41 lesions in 39 patients

Granulomatous Lung Diseases: A Practical Approach and Review of Common Entities

Granulomas are frequently encountered by pathologists in all types of lung specimens and arise from diverse etiologies. They should always be reported as necrotizing or non-necrotizing, with microorganism stains performed to evaluate for infection. With attention to distribution, quality (poorly vs well-formed), associated features, and correlation with clinical, radiologic, and laboratory data, the differential diagnosis for granulomatous lung disease can usually be narrowed to a clinically helpful "short list." This review describes a practical approach to pulmonary granulomas and reviews the clinicopathological aspects of common entities, including infectious (mycobacteria, fungi) and noninfectious (hypersensitivity pneumonitis, sarcoid, and vasculitis) causes.

Clinical Characteristics of Human Pulmonary Dirofilariasis in Japan: An Uncommon Differential Diagnosis of a Solitary Pulmonary Nodule

Human pulmonary dirofilariasis (HPD) is a zoonotic disease caused by Dirofilaria immitis. Most HPD cases are asymptomatic and are either detected during annual health checkups or incidentally identified during the investigation of other diseases, particularly primary or metastatic pulmonary lung cancers. However, the frequency and clinical features of Japanese patients with HPD remain unclear. We analyzed data from the Japanese Medical Abstract Society database and identified 69 cases between 1978 and 2022. The incidence of HPD increased until the 2000s but declined markedly in the 2010s. The incidence is higher in the southwestern region and lower in the northeastern region of Japan. Health checkups are the primary diagnostic opportunities. The Chugoku and Shikoku regions have had high incidence rates per population. The diagnosis of HPD using a noninvasive procedure is typically difficult because of the absence of specific clinical symptoms, and approximately 70% of the cases are detected using video-assisted thoracoscopic surgery. Climate change may increase the incidence of HPD in the northeastern region of Japan, and travel to countries with poor vector control may be a risk factor for HPD transmission. Physicians should consider this parasitic infectious disease when examining patients presenting with solitary lung nodules.

Human Pulmonary Dirofilariasis: A Review for the Clinicians

Human pulmonary dirofilariasis (HPD) is a rare zoonotic disease caused by Dirofilaria immitis, the nematode responsible for canine cardiopulmonary dirofilariasis (dog heartworm). The incidence of HPD is on the rise throughout the world due to increased awareness and factors affecting the vector (mosquito). Humans are accidental hosts for D. immitis. Most patients are asymptomatic and present with an incidental pulmonary nodule that mimics primary or metastatic pulmonary malignancy. Some patients suffer from pulmonary and systemic symptoms in the acute phase of pneumonitis caused by pulmonary arterial occlusion by the preadult worms resulting in pulmonary infarction and intense inflammation. These patients may have ill-defined pulmonary infiltrate on chest radiology. Pulmonary nodules represent the end result of initial pneumonitis. There are no specific clinical, laboratory, or radiologic findings that differentiate HPD from other causes of a pulmonary nodule. Although serologic tests exist, they are usually not commercially available. The majority of patients are diagnosed by histopathologic identification of the decomposing worm following surgical resection of the lesion.

[Features of granulomatous inflammation in helminthiasis, mycoses and human protozoal diseases in forensic medical practice]

THE AIM OF THE STUDY

Is to draw the attention of forensic experts and histologists to the problem of infectious diseases occurring with the formation of granulomas. Was reviewed the general patterns of granulomatous diseases, as well as the peculiarities of pathomorphosis in helminthiasis (schistosomiasis, paragonimiasis, onchocerciasis, dirofilariasis, ascariasis, cysticercosis), mycoses (cryptococcosis, chromomycosis, coccidioidosis) and protozoal diseases, toxosomes. The article includes photomicrographs from the authors' personal archive, including those collected during their work in African countries Text is based on scientific data from articles, monographs, educational literature, personal experience and cases of forensic medical practice.

Transesophageal Echocardiography–Guided Dirofilaria immitis Extraction from the Right Atrium in a Dog

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In Dirifilaria immitis infection, worms can migrate into the heart.

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Clinical signs are caused by hemolysis and and obstruction of blood flow.

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Transesophageal echocardiography guides removal of radiolucent foreign objects.

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TEE findings assisted in the extraction of intracardiac heartworms from a dog.

Pictorial Review of Thoracic Parasitic Diseases: A Radiologic Guide

Parasitoses are infectious diseases of global distribution, with predominance in areas of poor sanitation. Parasites cause damage through direct tissue injury and the inflammatory response generated by their migration and establishment in various organs. Thoracic involvement by parasitic disease can generate both specific and nonspecific clinical, laboratorial, and radiologic manifestations, which often makes their diagnosis challenging. The correct diagnosis is crucial for definition of treatment, which sometimes requires rapid intervention. Based on a literature review of the last few decades, this article aimed to characterize the main radiologic findings related to thoracic manifestations of parasitic diseases, correlating them with radiographic and tomographic images of patients with confirmed diagnosis of such pathologies. The included parasitic diseases are malaria, Chagas disease, toxoplasmosis, amoebiasis, ascariasis, toxocariasis, strongyloidiasis, dirofilariasis, cysticercosis, echinococcosis, schistosomiasis, and paragonimiasis.

Infectious Lung Disease

Infectious diseases are one of the main causes of morbidity and mortality worldwide. With new pathogens continuously emerging, known infectious diseases reemerging, increasing microbial resistance to antimicrobial agents, global environmental change, ease of world travel, and an increasing immunosuppressed population, recognition of infectious diseases plays an ever-important role in surgical pathology. This becomes particularly significant in cases where infectious disease is not suspected clinically and the initial diagnostic workup fails to include samples for culture. As such, it is not uncommon that a lung biopsy becomes the only material available in the diagnostic process of an infectious disease. Once the infectious nature of the pathological process is established, careful search for the causative agent is advised. This can often be achieved by examination of the hematoxylin and eosin-stained sections alone as many organisms or their cytopathic effects are visible on routine staining. However, ancillary studies such as histochemical stains, immunohistochemistry, in situ hybridization, or molecular techniques may be needed to identify the organism in tissue sections or for further characterization, such as speciation.

[Histological differential diagnosis of granulomatous lung diseases (Part II)]

Granulomatous diseases are a heterogeneous group of the diseases of different etiology, which are manifested by a variety of clinical syndromes and variants of tissue changes, by non-uniform sensitivity to therapy and by the predominance of the common dominant histologic sign - the presence of granulomas that determine the clinical and morphological essence of each disease. Granuloma is a chronic inflammatory response, which involves macrophages and other inflammatory cells. After antigen exposure, the activation of T lymphocytes, macrophages, epithelioid cells, and multinucleated giant cells results in granuloma formation. Granuloma also contains the extracellular matrix produced by fibroblasts, which can demarcate and isolate the antigen. Granulomatous diseases are classified by their etiology as infectious and non-infectious. However, recent investigations demonstrate that pathogenic microorganisms can cause granulomas in the diseases previously considered non-infectious. In some cases, it is very difficult to classify a granulomatous process as infectious and non-infectious. The aim of this paper is to draw the attention of readers to the diversity of granulomatous diseases, to describe the key points of pathological and anatomical manifestations of various infectious diseases, and to determine an approach to the differential diagnosis of granulomatoses.

Thirteen cases of pulmonary dirofilariasis in a single institution in Okinawa Island

Pulmonary dirofilariasis is an infection caused by Dirofilaria immitis, which is an endemic parasite in Japan. We experienced 13 surgical cases of pulmonary dirofilariasis in our hospital. Of the 13 patients, 61.5% were men. The responsible lesions were located in the right lung in all cases, and 76.9% of them were in the lower lobe. Histologically, 12 cases showed necrotic nodules with peripheral granuloma with worms inside the pulmonary artery. One case did not show a necrotic nodule but showed only thickening and hyalinization of the pulmonary artery wall with a degenerated worm inside. Eosinophils were found histologically in all cases. Thirteen cases of dirofilariasis in one institution seem to be the largest number in Japan, based on previous reports. One reason for this increased prevalence may be the hot and humid climate of our prefecture considering the ecology of the mosquito as a vector. Elastic staining and eosinophils in peripheral granulomatous areas can contribute to the diagnosis when the worms are degenerated.

Lung Infections

A review of pulmonary infections of all types with diagnostic and morphological features.

Eosinophilia in Infectious Diseases

In determining the etiology of eosinophilia, it is necessary to consider the type of patient, including previous travel and exposure history, comorbidities, and symptoms. In this review, we discuss the approach to the patient with eosinophilia from an infectious diseases perspective based on symptom complexes.

Man's best friend: How humans can develop Dirofilaria immitis infections

Canine heartworm, Dirofilaria immitis, is a nematode parasite that infects dogs by way of mosquito bite. Rarely, humans play accidental hosts to this parasite and are not a suitable environment for the nematode to live. As the parasite dies in the pulmonary vessels it embolizes the vessels causing infarction and eventual nodule formation in the lungs. In the right clinical context, a nodule can be considered malignant prompting invasive tissue sampling. We describe a case of a 48-year-old man who was found to have multiple asymptomatic scattered pulmonary nodules during imaging workup for an insulinoma. Fine needle biopsy of the largest nodule revealed a necrotic granuloma, lab testing and culture ruled out fungal and bacterial causes. Clinically, this picture was consistent with D. immitis infection.

A rare case of human pulmonary dirofilariasis with a growing pulmonary nodule after migrating infiltration shadows, mimicking primary lung carcinoma

INTRODUCTION

Pulmonary dirofilariasis is a rare pulmonary parasitic infection by the nematode Dirofilaria immitis. It is characterized by an asymptomatic pulmonary nodule usually seen on chest X-ray. The differential diagnosis of pulmonary dirofilariasis includes other pulmonary diseases, primary lung carcinoma and metastatic lung tumor.

CASE PRESENTATION

Pulmonary dirofilariasis was diagnosed in a woman who presented with interstitial pneumonia. Growth of the pulmonary nodule was detected subsequent to hemoptysis. The histological diagnosis was made based on a wedge resection performed under video-associated thoracic surgery (VATS).

CONCLUSION

Pulmonary dirofilariasis often varies in its clinical course. The diagnosis is best made using wedge resection under VATS.

A 72-Year-Old Woman With Previous Pulmonary Metastasis and New Peripheral Nodule

A 72-year-old female nonsmoker was admitted to our Thoracic Surgery Unit in 2013 because of a lesion detected on chest CT scan during oncologic follow-up. Her medical history was significant for the development of a single pulmonary metastasis discovered 1 year after sigmoidectomy for colic adenocarcinoma. At that time, the patient was treated with six cycles of neoadjuvant chemotherapy followed by left lower lobectomy. Histologic examination demonstrated a pulmonary metastasis of colic adenocarcinoma with diffuse necrotic areas. The patient underwent subsequent adjuvant chemotherapy with capecitabine and was followed annually with biohumoral oncologic screening (carcinoembryonic antigen, carbohydrate antigen 19-9), chest-abdomen CT scan, and colonoscopy.

18-FDG Uptake in Pulmonary Dirofilariasis

Solitary pulmonary nodules are a common finding on chest radiography and CT. We present the case of an asymptomatic 59-year-old male found to have a 13 mm left upper lobe nodule on CT scan. The patient was asymptomatic and the CT was performed to follow up mediastinal and hilar lymphadenopathy that had been stable on several previous CT scans. He had a history of emphysema and reported a 15 pack-year smoking history. PET-CT was performed which demonstrated mild 18-FDG uptake within the nodule. Given his age and smoking history, malignancy was a consideration and he underwent a wedge resection. Pathological examination revealed a necrobiotic granulomatous nodule with a central thrombosed artery containing a parasitic worm with internal longitudinal ridges and abundant somatic muscle, consistent with pulmonary dirofilariasis. Dirofilaria immitis, commonly known as the canine heartworm, rarely affects humans. On occasion it can be transmitted to a human host by a mosquito bite. There are two major clinical syndromes in humans: pulmonary dirofilariasis and subcutaneous dirofilariasis. In the pulmonary form, the injected larvae die before becoming fully mature and become lodged in the pulmonary arteries.

Pulmonary dirofilariasis in a 59-year-old man

We present a case of a human pulmonary dirofilariasis in a 59-year-old man. At the medical examination, a chest computed tomography (CT) revealed a mass, measuring 18 × 15 mm in diameter, with an irregular margin on the bottom of the right lower lobe. We could not neglect the possibility of a primary lung cancer, and therefore, a lung partial resection was performed under video-assisted thoracoscopic surgery. The intra-operative pathological findings revealed inflammatory granuloma with coagulation necrosis and no malignant cells. The permanent pathological examination showed occlusion of the peripheral pulmonary artery by worms and formation of a necrotic mass surrounded by reactive inflammation and hemorrhage. Human pulmonary dirofilariasis is an extremely rare zoonotic infection, and sometimes it is difficult to distinguish it from a primary lung cancer on radiographic findings.

A case of human pulmonary dirofilariasis in a 48-year-old Korean man

Dirofilariasis is a rare disease in humans. We report here a case of a 48-year-old male who was diagnosed with pulmonary dirofilariasis in Korea. On chest radiographs, a coin lesion of 1 cm in diameter was shown. Although it looked like a benign inflammatory nodule, malignancy could not be excluded. So, the nodule was resected by video-assisted thoracic surgery. Pathologically, chronic granulomatous inflammation composed of coagulation necrosis with rim of fibrous tissues and granulations was seen. In the center of the necrotic nodules, a degenerating parasitic organism was found. The parasite had prominent internal cuticular ridges and thick cuticle, a well-developed muscle layer, an intestinal tube, and uterine tubules. The parasite was diagnosed as an immature female worm of Dirofilaria immitis. This is the second reported case of human pulmonary dirofilariasis in Korea.

[A case of pulmonary dirofilariasis with a single nodule on an apical lesion of the right upper lobe]

A 75-year-old man with chronic gastritis and gastro-esophageal regurgitation syndrome was admitted to our hospital complaining of continuous productive cough, and an abnormal shadow was noted on a chest X-ray film. Chest computed tomography revealed a nodule 2.8 cm in diameter with a regular margin on the right apex. Fiberoptic bronchoscopy was performed, but did not yield a definitive diagnosis. We suspected primary lung cancer, and therefore, lung partial resection was performed under thoracoscopic surgery. The intraoperative pathological findings revealed inflammatory granuloma with necrosis, and pulmonary dirofilariasis was finally diagnosed. Pulmonary dirofilariasis is an important differential diagnosis in elderly patients with a chest abnormal nodular shadow. Lesions have been reportedly observed in the peripheral portion of the right lower lobe in many previous reports. However, in this case, a nodular lesion was noted in the right apex.

Granulomatous lung disease: an approach to the differential diagnosis

CONTEXT

Granulomas are among the most commonly encountered abnormalities in pulmonary pathology and often pose a diagnostic challenge. Although most pathologists are aware of the need to exclude an infection in this setting, there is less familiarity with the specific histologic features that aid in the differential diagnosis.

OBJECTIVE

To review the differential diagnosis, suggest a practical diagnostic approach, and emphasize major diagnostically useful histologic features. This review is aimed at surgical pathologists who encounter granulomas in lung specimens.

DATA SOURCES

Pertinent recent and classic peer-reviewed literature retrieved from PubMed (US National Library of Medicine) and primary material from the institutions of both authors.

CONCLUSIONS

Most granulomas in the lung are caused by mycobacterial or fungal infection. The diagnosis requires familiarity with the tissue reaction as well as with the morphologic features of the organisms, including appropriate interpretation of special stains. The major noninfectious causes of granulomatous lung disease are sarcoidosis, Wegener granulomatosis, hypersensitivity pneumonitis, hot tub lung, aspiration pneumonia, and talc granulomatosis.

A case of Dirofilaria pulmonary infection coexisting with lung cancer

Dirofilaria immitis, the dog heartworm, may accidentally infect humans and manifest as a subpleural solitary or multiple pulmonary nodules that are often difficult to differentiate from primary or metastatic lung tumors. Our patient had biopsy proven lung cancer and a second lesion found to be pulmonary dirofilariasis after excision. The coexistence of pulmonary infection and cancer must be considered whenever 2 or more lesions have different clinical and radiologic behavior. Pulmonary dirofilariasis is a rare cause of lung nodules and may be present with lung cancer even more infrequently.

Pulmonary Vascular Disease

The pulmonary vasculature is an anatomic compartment that is frequently overlooked in the histologic review of lung biopsy samples, other than those obtained specifically to assess pulmonary vascular disease.1 Though often of a nonspecific nature, the histologic pattern of vascular remodeling may at times suggest its underlying pathogenesis and provide clues to the cause of pulmonary hypertension.2 Disproportionately severe vascular pathology may further indicate alternate disease processes, such as congestive heart failure or thromboemboli, contributing to the patient’s overall respiratory condition.

Allergic inflammatory reaction is involved in necrosis of human pulmonary dirofilariasis

AIMS

To determine whether, in view of the massive inflammatory cell infiltration and the rounded rather than wedge-shaped character of pulmonary lesions in dirofilariasis, the inflammatory response against the worm contributes to the coagulative necrosis, in addition to an ischaemic process.

METHODS AND RESULTS

The histopathological features of 13 resected dirofilariasis cases with well-defined nodules ranged from 10 to 30 mm were analysed. On routine histology and using immunohistochemistry, the peripheral encapsulating wall showed mild to severe infiltration of eosinophils, lymphocytes and plasma cells and a histiocytic reaction in all cases, often with necrotic eosinophils seen within the necrosis (84.6%) and inflammatory changes in the adjacent lung (38.5%). The CD4+ lymphocyte count (80.8 +/- 33.4) was greater than that of CD8+ lymphocytes (24.5 +/- 16.9) in the central necrosis and vice versa in the wall. In the necrotic regions, disruption of the pulmonary artery (61.5%) and extravasation of the torn worm (23.1%) could be seen.

CONCLUSIONS

These findings indicate that an allergic inflammatory reaction, mediated by eosinophils and lymphocytes, is involved in the formation of the dirofilarial necrotizing granuloma rather than infarction caused simply by embolism.

Pathological diagnosis of granulomatous lung disease: a review

Granulomas in the lung are common diagnostic problems encountered by pathologists. They occur in a wide range of pulmonary conditions, ranging from common entities to uncommon ones and including both infections and non-infectious diseases. This review summarizes the main histological features that help distinguish various granulomatous lung diseases. It concentrates on the most important and common entities that may be encountered and emphasizes helpful features in the differential diagnosis.

PET Findings in Pulmonary Dirofilariasis

This case demonstrates hypermetabolic activity in a pulmonary round infarct secondary to dirofilariasis. This case further illustrates that pulmonary dirofilariasis, like other infectious causes of pulmonary nodules, can be PET positive.

Pulmonary Dirofilariasis

OBJECTIVE

The purpose of this study was to describe the computed tomography (CT) and pathologic features of 5 nodules of pulmonary dirofilariasis in 4 patients.

METHODS

Four patients with 5 nodules of pathologically confirmed pulmonary dirofilariasis who under went CT were enrolled, and the imaging interpretations were retrospectively compared with the histopathologic characteristics.

RESULTS

Three of the 4 patients had a solitary nodule, and the remaining patient had 2 nodules. All the nodules were distributed in the right lower lobe and were attached to the pleura. They were all round or oval in shape and ranged in size from 11 to 22 mm in largest diameter (mean=17 mm). On thinner section CT, the nodules had a well-defined smooth margin with or without a shallow notch; they were connected to the arterial branch and, occasionally, to the venous branch. On contrast-enhanced CT, all the nodules contained a homogeneous low-attenuation area, which corresponded to areas of coagulative necrosis on histopathologic examination.

CONCLUSION

Although the CT findings of a pulmonary dirofilariasis nodule are nonspecific, awareness of the findings on contrast-enhanced CT and the pathologic appearance of this rare benign condition may facilitate its differentiation from a malignant nodule.

Dirofilariose pulmonar humana: relato de sete casos

Dirofilariose pulmonar humana é uma doença rara causada pelo parasita Dirofilaria immitis. Apresenta-se usualmente como um nódulo pulmonar solitário que mimetiza câncer de pulmão. Embora considerada uma doença clinicamente benigna, uma biópsia pulmonar excisional é quase sempre necessária para o diagnóstico. Relatam-se as características epidemiológicas, clínicas e radiológicas de sete casos de dirofilariose pulmonar humana em Florianópolis. De sete pacientes relatados, seis tiveram como achado radiológico um nódulo pulmonar e foram submetidos à biópsia pulmonar excisional para o diagnóstico. Em um paciente, a imagem radiológica não estava disponível para revisão e, portanto, não foi descrita no trabalho; o diagnóstico foi estabelecido pela biópsia transbrônquica.

Rheumatic manifestations of parasitic diseases

OBJECTIVES

To consolidate the spectrum and frequency of parasite-related rheumatic syndromes, which have largely been regarded as exceedingly rare by the general medicine, infectious disease, and rheumatology literature.

METHODS

A MEDLINE search was performed for articles on rheumatic syndromes related to parasitic infections published from 1966 through December 2000. Identified articles included clinical and epidemiologic studies describing cases of rheumatic syndromes associated with verified parasitic infection.

RESULTS

Rheumatologic syndromes, including inflammatory arthritis, inflammatory myositis, and vasculitis, have been described among multiple different parasite infections of all parasitic divisions, including Protozoa, Nematoda, and Platyhelminthes. Individual parasitic divisions are often associated with particular rheumatic syndromes, such as reactive arthritis and spondyloarthropathy, inflammatory or infectious myositis, and reactive or parainfectious vasculitis.

CONCLUSIONS AND RELEVANCE

Parasitic infection may underlie the clinical presentation of some rheumatic conditions. Given the continued and growing number of patients at risk for parasitosis by virtue of their country of origin, travel habits, and an immunocompromised state, potential parasitosis must be considered in patients undergoing evaluation for rheumatic complaints.

Human pulmonary dirofilariasis: report of six cases

We report six cases of pulmonary dirofilariasis diagnosed at our laboratory with clinical and pathological features. The nodules of dirofilariasis were round in three cases as previously reported, however dumbbell-shaped in two cases. The nodule did not attach to the pleura in four cases. Microscopically, the nodules were granulomas composed of central coagulation necrosis and peripheral fibrosis with round cell infiltration, histiocytes, and multinucleated giant cells. Necrotic pulmonary artery with single or multiple sections of degenerated nematode was observed in the center of the nodule. Dilated bronchioles with inflammation were observed in the nodule in four cases. Collapse of the alveoli, organizing pneumonia, hemosiderin-laden macrophages were observed around the nodule. We suppose that the nodule is not an infarction but a granuloma caused by antigen released from the nematode. Because the pulmonary dirofilariasis is difficult to be differentiated from primary or metastatic lung carcinoma, and the inflammation exists around the nodule, the nodule should be removed surgically.