Mycoplasma pneumoniae-associated bronchiolitis causing severe restrictive lung disease in adults: report of three cases and literature review

Abstract

Study objectives: To characterize adult Mycoplasma pneumoniae-induced bronchiolitis requiring hospitalization.

Design: We encountered an adult patient with severe bronchiolitis in the absence of pneumonia due to M. pneumoniae. To determine the relative frequency of such a condition, we retrospectively reviewed the medical records of adults over a 4-year period with a hospital discharge diagnosis of "bronchiolitis" from a university hospital.

Setting: University Hospital of the University of Colorado Health Sciences Center, Denver, CO.

Study subjects: From 1994 to 1998, 10 adult inpatients were identified with a diagnosis of bronchiolitis. There were two with respiratory bronchiolitis, one with panbronchiolitis, one patient with bronchiolitis obliterans organizing pneumonia (BOOP), and six with acute inflammatory bronchiolitis. Including the initial patient, three had a definitive clinical diagnosis of Mycoplasma-associated bronchiolitis.

Results: The three adult patients with bronchiolitis due to M. pneumoniae are unusual because they occurred in the absence of radiographic features of a lobar or patchy alveolar pneumonia. Hospital admission was occasioned by the severity of symptoms and gas exchange abnormalities. One patient had bronchiolitis as well as organizing pneumonia (BOOP) that responded favorably to corticosteroid treatment. The other two had high-resolution CT findings diagnostic of an acute inflammatory bronchiolitis. One of the patients with inflammatory bronchiolitis had an unusual pattern of marked ventilation and perfusion defects localized predominantly to the left lung. All three had restrictive ventilatory impairment on physiologic testing.

Conclusions: In adults, Mycoplasma-associated bronchiolitis without pneumonia is rarely reported, but in hospitalized patients, it may be more common than expected and may be associated with severe physiologic disturbances.

Figure 1

Chest radiograph of patient 1, demonstrating a fine nodular interstitial pattern, especially at the bases.

Figure 2

Left, A: lung micrograph of patient 1 showing granulation tissue (Masson's body, arrow), projecting into a respiratory bronchiole through the site indicated by the dashed arrow (pentachrome, original magnification ×200). Note the presence of mucus more proximally in the bronchiolar lumen. Right, B:granulation tissue cast filling an alveolar duct (arrow). Note the presence of branching cast of granulation tissue composed of elongated fibroblasts admixed with lymphoplasmacytic infiltrate (hematoxylin-eosin, original magnification ×400).

Figure 3

Top: Posterior view of ^99mTc-DTPA aerosol ventilation scan of patient 2 showing severely reduced ventilation to the left lung, with a more patchy decrease in ventilation of the right lung. Bottom:corresponding image of ^99mTc-MAA perfusion scan shows matching areas of decrease in perfusion.

Figure 4

HRCT scan of patient 2, retargeted to the left lung, shows fine centrilobular nodules (arrows) compatible with an inflammatory bronchiolitis.

Figure 5

HRCT scan of chest of patient 3 shows diffuse centrilobular nodularity (“tree in bud” appearance, arrow) consistent with inflammatory bronchiolitis.