Pulmonary actinomycosis in fine needle aspiration cytology.

Pulmonary actinomycosis is a rare bacterial lung disease caused by one of two types of bacteria, Actinomyces or Propioni. Pulmonary actinomycosis in the lung causes lung cavities, lung nodules, and pleural effusion. We report here a case of pulmonary actinomycosis that was diagnosed by fine needle aspiration cytology (FNAC). A 45 year-old male with a history of smoking and alcohol abuse, presented with complaints of cough with hemoptysis, right-sided chest pain, and fever of two months' duration. A chest radiograph and computed tomography (CT) of the thorax showed a right upper lobe mass lesion with hilar lymphadenopathy. CT-guided FNAC revealed colonies of Actinomyces surrounded by polymorphs. The disease is commonly confused with other chronic suppurative lung diseases and malignancy. An early diagnosis by FNAC prevents difficulties in the management of the disease, as well as considerable physiological and physical morbidity, including unwarranted surgery.

Introduction

Pulmonary actinomycosis is a difficult clinical condition to diagnose even by experienced physicians. Despite clues suggestive of the disease, delayed diagnosis or misdiagnosis as tuberculosis, lung abscess, or lung carcinoma is common.[1] The disease is rare, showing a male preponderance, and may occur at any age; most patients are, however, 30–60 years old. Alcohol abuse, bronchiectasis, and emphysema are also associated with actinomycosis. Diagnosis using fine needle aspiration cytology (FNAC) also requires awareness of the disease. We report here a case of pulmonary actinomycosis that was diagnosed by computed tomography (CT)-guided FNAC and presented clinically with differential diagnoses of pulmonary tuberculosis and malignancy.

Case Report

A 45 year-old male presented in the outpatient department of our hospital with complaints of cough with hemoptysis, right-sided chest pain, and fever of two months’ duration. Respiratory system examination revealed an emphysematous chest and the presence of right-sided crepitations; other organ systems were functioning within the normal range. The patient was anaemic with a haemoglobin level of 9.4 g/dL. Other investigations including blood sugar level were also within normal limits. Sputum examinations (three consecutive samples) were negative for acid-fast bacilli, malignant cells, or fungal elements; HIV serology was negative. A chest radiograph showed a right upper lobe mass lesion with hilar lymph nodes, raising the suspicion of a malignancy [Figure 1]. CT scan of the thorax revealed a right upper lobe, anterior segment, inhomogeneous, enhancing mass lesion with perifocal consolidation with right hilar lymphadenopathy [Figure 2].

Figure 1

Chest radiograph film showing a peripheral well defined opacity on right side upper and mid zones

Figure 2

Computed tomography scan showing a right upper lobe anterior segment mass lesion with perifocal consolidation with right hilar lymphadenopathy

Bronchoscopy revealed normal airways and mucosa and bronchoalveolar lavage was negative for malignant cells or fungal elements. CT-guided FNAC was done from the right lung mass lesion. The smears were prepared and stained with haematoxylin and eosin, periodic acid Schiff (PAS), and Giemsa stains. The smears revealed radiating filamentous colonies of Actinomyces in a background of neutrophilic exudates; PAS stain also showed Actinomyces colonies [Figure 3], resulting in the confirmation of the diagnosis of pulmonary actinomycosis. The patient was treated with intravenous penicillin for fifteen days and then given oral clindamycin plus doxycycline for six months besides other symptomatic treatment. The patient responded well to the above treatment; this was confirmed in the follow-up radiological examination at the end of six months as reduced lung shadows.

Figure 3

Colonies of radiating filamentous Actinomyces surrounded by neutrophils (PAS, ×400)

Discussion

Actinomycosis is a subacute to chronic bacterial infection caused by filamentous, gram-positive, anaerobic to microaerophilic bacteria that are not acid-fast. This report describes a patient with pulmonary infection of actinomycosis, which is usually associated with chronic smoking and alcoholism. In addition to the difficulties in clinically diagnosing actinomycosis, our case was further complicated by the presence of hemoptysis. Hemoptysis was the major presenting symptom in our case though massive hemoptysis due to pulmonary actinomycosis has rarely been reported.[2] Massive hemoptysis commonly occurs due to bronchiectasis, tuberculosis, bronchogenic carcinoma, lung abscess, and aspergilloma. Other systemic symptoms such as fever and weight loss were also noted. Poor oral hygiene allows the normal flora to flourish. Aspiration of the infected material is the presumptive mechanism that leads to thoraco-pulmonary infection.[3] The clue pointing to the subacute infection in this patient was prolonged, low-grade fever with recurrent, blood-streaked sputum. Care is necessary as tuberculosis is the more common disease in our country and an important differential diagnosis in this setting of upper lobe infiltration that was seen on imaging. Other causative agents that mimic tuberculosis should also be considered, including meliodosis, histoplasmosis, nocardiosis, and actinomycosis.[4]

Baik et al.[5] reported 25 cases of pulmonary actinomycosis in Korea. Hemoptysis was the most common clinical symptom occurring in 72% of the patients. Systemic symptoms such as fever and weight loss were also noted. Chest radiographs showed mass-like lesions, as well as consolidated or localized bronchiectatic changes. Thoracotomy was performed to exclude malignancy. Thus, the diagnosis of pulmonary actinomycosis is often difficult. In many cases, antituberculous medications have been administered without any improvement, and surgical resections have been frequently performed due to a suspicion of lung cancer.

Invasive investigations like bronchoscopy with transbronchial biopsy are necessary in order to obtain samples for histological and microbiological identifications to make a diagnosis of pulmonary actinomycosis. Although it is now a rare disease with a very low mortality rate, microbiological confirmation can still be difficult even if there is a strong clinical suspicion. The disease shares many similar clinical features with chronic suppurative lung infection, such as tuberculosis, fungal infection, lung abscess, and lung malignancy with which it is commonly confused. Plain chest radiograph findings in actinomycosis are nonspecific although the spectrum of changes is wide, ranging from a few pulmonary infiltrates to cavitary mass lesions. Limited additional information is available from computed tomography. A range of findings have been described with CT in pulmonary actinomycosis, including patchy air-space consolidation, multifocal nodular appearance, cavitation, pleural thickening, pleural effusion, and hilar and mediastinal lymphadenopathy. Bronchoscopy is usually not diagnostic in pulmonary actinomycosis unless there is clear endobronchial disease on which biopsy can be performed. Bronchoalveolar lavage may be falsely negative if the material is exposed to air for more than 20 minutes. Fine needle aspiration technique guided by CT or ultrasound has been proven to be a simple, safe, and effective diagnostic technique that reduces the number of unnecessary resections and also avoids difficulties in the management of the disease.[67] Cytologically, the bacteria is identified by their growth pattern in colonies made up of dense masses of hematoxylin-stained, tangled filaments that radiate outward and tend to be eosinophilic at the periphery.[8] The polymerase chain reaction (PCR) technique has been developed for the diagnosis of actinomycosis.

Pulmonary actinomycosis is rare, but should be considered in the differential diagnoses of a subacute pulmonary infection followed by hemoptysis, and sometimes, also mimicking malignancy. Therefore, an early diagnosis by FNAC is warranted for effective antibiotic therapy and surgical resection. Prolonged treatment with antibiotics (penicillin or amoxicillin) is indicated to ensure that the disease is cured.