Mediastinal Actinomycosis: A Rare Mediastinal Pseudotumour

Abstract

Actinomycosis, once fairly common and often catastrophic, has now become an occasional infection in the era of antibiotics. The infection is caused by a branching Gram-positive, facultative anaerobic microorganism Actinomycetes. Various forms of the diseases in decreasing order of their frequency include cervico-facial form, abdomino-pelvic form and thoracic form. The thoracic involvement occurs in approximately 15% of all cases of actinomycosis. The disease presents with nonspecific signs and symptoms and therefore establishment of a definitive diagnosis with clinical and radiological investigations is difficult. The clinical and radiological picture mimics a number of other pulmonary conditions like cancer, tuberculosis, lung abscess and pneumonia. To reach at a definitive diagnosis one needs to have a high degree of suspicion and carry out histopathological studies in order to look for colonies of Actinomycetes as well as sulphur granules which are pathognomic for the infection. Here is a case of a 48-year-old diabetic male presenting with complaints of pain and swelling of neck, fever, dysphagia, dyspnea and cough with a mediastinal tumour like appearance on chest radiography. The patient underwent various noninvasive and invasive diagnostic modalities that included Contrast Enhanced Computed Tomography (CECT), Ultrasonography (USG) of thorax and histopathological examination of the cervical lymph nodes (level 2 and 3). The disease process was initially thought to be tubercular or malignant in origin which later turned out to be an actinomycotic lesion which was confirmed on the histopathological study of the lymph node specimen, that responded to antibiotics over a period of few months.