High resolution computed tomography in cotton-induced lung disease.

Sir,

We read a recent article “An unusual interstitial lung disease,” with great interest, published in the postgraduate clinical section of your journal.[1]

The case deals with a 48-year-old nonsmoker, cotton mill worker, exposed to cotton dust for 27 years. The patient's clinical presentation, spirometry findings, and transbronchial lung biopsy picture, as suggested by the authors, are consistent with cotton-induced pneumoconiosis.

The authors have provided a high resolution computed tomography (HRCT) axial image of the patient and described the presence of multiple, well-defined centrilobular nodules with tree-in-bud appearance. However, in addition to these findings, there is evidence of mild central cylindrical bronchiectasis, bronchiolectasis, and mosaic attenuation. The constellation of these findings along with centrilobular nodules suggest the diagnosis of bronchiolitis and denote small airway disease.[2]

The HRCT imaging findings of lung fibrosis suggesting an interstitial pattern of lung involvement manifest as thickening of the interstitium, either peribronchovascular or centrilobular, and there may be ground glass opacities in addition. A similar case of diffuse lung disease caused by cotton fiber inhalation and distinct from byssinosis, also provided as a reference by the authors, also describes similar findings on HRCT. These include subpleural ground-glass opacities with centrilobular and peribronchovascular interstitial thickening.[3]

We agree with the authors that cotton-induced airway disease is indeed common and pulmonary fibrosis secondary to cotton exposure is rarely reported. However, the provided HRCT image suggests the diagnosis of bronchiolitis, reflecting airway disease and does not necessarily corroborate with findings of pulmonary fibrosis or interstitial lung disease.