INTRODUCTION: The right middle lobe (RML) syndrome, also know as Brock's syndrome, represents atelectasis in that part of the lung caused by many different etiologies. Those can be airway disease, extra and intraluminal obstructions or infectious. In this case, two entities were involved in the development of the syndrome: an inherited airway disease, primary ciliary diskinesia (PCD) and a Mycobacterium avium intracellulare (MAI) infection.
CASE PRESENTATION: A 38-year-old white woman was seen in the pulmonary clinic due to chronic complaints of productive cough, dyspnea and fatigue. She carried a diagnosis of PCD since age 15. The physical exam was unremarkable except for the presence of crackles in the right lung field. A Chest computed tomography (CT) demonstrated severe scaring and bronchiectasis within the RML. The pulmonary function tests showed moderate obstructive lung disease and a low DLCO. Sputum cultures demonstrated growth of both Pseudomonas aeruginosa and Haemophilus influenzae at that time. She was treated with antibiotics and inhaled bronchodilators with a modest response. A chest CT performed one year later showed persistent bronchiectasis within the RML and new “tree in bud” pattern compatible with granulomatous infections such as atypical mycobecterial infections (Figure). Broncho-alveolar lavage cultures from the RML during a bronchoscopic evaluation grew Mycobacterium fortuitum and MAI. The current plan is for antimycobacterial therapy directed against both Mycobacterium fortuitum and MAI. She will also undergo right middle lobectomy as it appears that this lobe is the major source of symptoms and can possibly spread her current infections to other lung segments.
DISCUSSIONS: The RML syndrome has been extensively discussed in the pulmonary literature. This area of the lung has a particular predisposition to accumulate secretions and to develop infections and bronchiectasis. Primary ciliary diskinesia is a rare autosomal recessive disorder caused by many different genetic mutations that as a common end point alters the normal motility of the cilium, which predisposes the lungs to recurrent infections (1). There are just few case reports linking PCD with atypical mycobacterial infections, which is probably due to under recognition (2). We did recover two types of mycobacterium in the first bronchoscopy (M. fortuitum and M. avium intracellulare). The differentiation between colonization and infection here is not easy to establish. Due to the overall clinical picture, this patient will probably benefit from antimycobacterial therapy.
CONCLUSION: This case represents a therapeutic challenge because of the coexistence of a systemic condition, PCD, that did cause bronchiectasis in a vulnerable lung area, the RML. More over, this area became infected with organisms that are generally difficult to treat; atypical mycobacteria. The treatment decisions here are difficult. The most conservative options could lead to future damage of the lung, and progression to end stage lung disease based upon spread of infection from the RML. The most aggressive option, lobectomy, carries some significant risk and is only supported in the literature by case series.
DISCLOSURE: Sajive Aleyas, None.