Original Articles Right Middle Lobe Atelectasis Associated With Endobronchial Silicotic Lesions Hsiu-Ping Chien, MD; Tao-Ping Lin, MD; Hsiao-Ling Chen, MD; Thomas W. Huang, MD c Background.ÐIn a period of 18 months, we have en- been excluded by careful radiographic and computed to- countered 4 cases of right middle lobe atelectasis associ- mographic image analysis. ated with endobronchial silicotic lesions of right middle Results.ÐThe endobronchial silicosis does not appear to lobe bronchi. All patients had occupational exposure to correlate with the degree of pneumoconiosis of the lung parenchyma. The endobronchial silicosis may cause bron- mineral dusts (3 coal miners and 1 sand blaster) for months chial obstruction in the absence of radiographic evidence to decades. of pulmonary silicosis. Methods.ÐThe nature of the endobronchial silicotic le- Conclusion.ÐThe endobronchial silicosis and conse- sions that caused the bronchial obstruction has been con- quent lung atelectasis may be associated with silica expo- ®rmed by endobronchial biopsies and energy-dispersive sure. spectrometry of the lesions. Extrinsic compression has (Arch Pathol Lab Med. 2000;124:1619±1622) he accumulation of mineral dusts in lung parenchyma, The endobronchial biopsy specimens from all 4 cases were T causing pneumoconiosis, is a well-known occupation- ®xed in sodium acetate±buffered 10% formalin solution and pro- al hazard. The translocation of mineral dusts through the cessed for paraf®n embedding. Four-micrometer sections were tracheobronchial-epithelial barrier into lamina propria of cut and stained with hematoxylin-eosin for light microscopy. For energy-dispersive x-ray microanalysis, multiple 10-mm-thick sec- the bronchial mucosa has been well documented. Silica tions were obtained from the paraf®n block of case 1, collected crystals may accumulate in the bronchial mucosa and in- in a test tube, and deparaf®nized with Hemo-De (Fisher Scien- 1±4 duce local pathological alterations. They rarely cause ti®c, Pittsburgh, Pa). The tissue pellets were obtained by centri- clinically signi®cant disease. We describe 4 cases of right fugation, and Hemo-De was substituted with ethanol followed middle lobe (RML) syndrome associated with obstructive by repeated washing in Tris-buffered saline. The tissues were silicotic nodules of bronchial mucosa. The narrowing and further digested with pronase (Fluka Chemika-Biochemica, obstruction of the RML bronchi were presumably caused Buchs, Switzerland). The residues after pronase digestion were by silicosis of bronchial mucosa. The possibilities of ex- repeatedly washed with double-distilled water. A drop of the sus- trinsic compression by enlarged lymph nodes had been pension of the residues was applied to a stub, air-dried, and car- excluded by careful radiographic and computed tomo- bon coated. The specimens were subjected to element analysis by an energy-dispersive spectrometer (Kevex, level 4). graphic (CT) image analysis. METHODS RESULTS After encountering the ®rst case of RML atelectasis associated Case Studies with obstructive endobronchial silicotic lesions in February 1996, we had seen a total of 4 cases during an 18-month period, from Case 1. A 64-year-old man, a nonsmoker and a coal February 1996 to August 1997. The cases were among those seen miner for more than 30 years, visited our outpatient de- at the Taiwan Provincial Chronic Disease Bureau, an institute es- partment with the chief complaint of productive cough off tablished to care for occupational lung diseases, pulmonary tu- and on for approximately half a year. Chest radiographs berculosis, and other chronic thoracic diseases. showed RML atelectasis with minimal ®brotic change over Chest radiography (both posteroanterior and lateral views), the right upper lung ®eld. Chest CT scan also revealed bronchoscopy with brushing cytologic tests, smears for acid-fast similar features. There was no evidence of lymphadenop- bacilli (AFB), and biopsies were performed on all patients. Spu- athy, which may compress or invade into the RML bron- tum cultures for AFB were also routinely performed. Pneumo- chus (Figure 1). No evidence of pneumoconiosis was not- coniosis of the lung parenchyma was diagnosed and classi®ed ed by CT scan and chest x-ray ®lms according to ILO according to the International Labour Of®ce (ILO) classi®cation of 1980.5 Three patients also received chest CT scans. classi®cation. Bronchoscopy showed near-total occlusion of ori®ce of RML bronchus, which showed markedly in- ¯amed mucosa with anthracotic pigmentation. Brush cy- Accepted for publication May 10, 2000. tologic test results and acid-fast staining were nonreveal- From the Taiwan Provincial Chronic Disease Control Bureau (Drs ing. The results of 3 consecutive sputum cultures for AFB Chien and Lin) and Taipei Institute of Pathology (Drs Chen and Huang), Wan-Shun-Liau, Shen-Keng Shiang, Taipei County, Taiwan. were also negative. Chest x-ray ®lms showed no signi®- Reprints: Hsiu-Ping Chien, MD, Taiwan Provincial Chronic Disease cant change after 18 months of follow-up. Control Bureau, 67±1, Wan-Shun-Liau, Shen-Keng Shiang, Taipei Case 2. A 76-year-old man, a coal miner for 7 years, County, Taiwan 222. was a former 30-pack-year cigarette smoker. He visited our Arch Pathol Lab MedÐVol 124, November 2000 Atelectasis and Endobronchial SilicosisÐChien et al 1619 Figure 1. Computed tomogram of the chest of case 1 showed right middle lobe atelectasis. The mediastinal nodes were not enlarged, and the evidence of potential external compression was absent. Figure 2. Large collections (indicated by arrows) of anthracotic pigment±laden macrophages in right middle lobe bronchial mucosa of case 1 beneath the basement membrane of respiratory epithelium (arrowheads) (hematoxylin-eosin, original magni®cation 3480). Figure 3. Polarizing microscopy of Figure 2 revealed numerous needle-shaped birefringent crystals in the macrophages (original magni®cation 3135 [a] and 3480 [b]). clinic for regular physical checkups. Chest radiograms re- x-ray ®lms showed no signi®cant change after 9 months vealed atelectasis of RML without hilar lymphadenopathy. of follow-up. The lung ®eld showed category 1 simple pneumoconiosis. Case 3. A 65-year-old man, a coal miner for several Bronchoscopy revealed a total obliteration of RML bron- months, was a former 4-pack-year cigarette smoker who chial ori®ce, with severely in¯amed mucosa and anthra- had productive cough for more than 2 years. Chest radio- cotic pigmentation. Bronchial brush cytologic test results graphs revealed RML partial atelectasis. Chest CT scan and acid-fast staining were nonrevealing. One set of spu- showed RML partial atelectasis without evidence of hilar tum culture for AFB also revealed negative results. Chest lymphadenopathy. No evidence of pneumoconiosis was 1620 Arch Pathol Lab MedÐVol 124, November 2000 Atelectasis and Endobronchial SilicosisÐChien et al Demographic and Clinical Data of Patients* Bronchial Brush Case No./ Cytologic AFB AFB Sex/Age, y Occupation ILO Classes Test Result Smear Culture² 1/M//64 Coal miner .30 y No pneumoconiosis 222(3) 2/M/76 Coal miner 7 y Category 1 pneumoconiosis 222(1) 3/M/65 Coal miner several months No pneumoconiosis 222(1) 4/M/64 Sand blaster 20 y Category B pneumoconiosis 222(2) * ILO classes indicates International Labour Of®ce lung x-ray classes; AFB smear, bronchial brush acid-fast bacilli smear; AFB culture, sputum acid-fast bacilli culture; minus sign, negative. ² Numbers in parentheses indicate the number of patients with this result. noted from image studies. Bronchoscopy with biopsy location of mineral dusts through tracheobronchial epithe- showed near total occlusion of lateral segment of RML lial barrier into the lamina propria of the bronchial mu- bronchus ori®ce due to elevated mucosa with anthracotic cosa has been observed.1±4 Mineral dusts on the surface of pigmentation. Bronchial brush cytologic test results and the bronchial mucosa can be phagocytized by macrophag- acid-fast staining were nonrevealing. One set of sputum es, which either are expelled by the mucociliary escalator culture for AFB also yielded negative results. The patient or migrate through the epithelial barrier into the bronchial was lost to follow-up thereafter. mucosa. Some of the mineral dusts can directly translocate Case 4. A 64-year-old man, a sand blaster for 20 years, into the bronchial mucosa without the help of macrophag- was a former 15-pack-year cigarette smoker. He had cough es. Even in the absence of dust overload, a certain fraction with exertional dyspnea for 4 years, which worsened in of deposited particles make their way into bronchial mu- recent days. Chest CT scan and plain chest ®lms revealed cosa.6,7 In case of dust overload, a corresponding increase RML and right upper lobe partial atelectasis associated in particle uptake by the bronchial mucosa occurs. The with category B pneumoconiosis of the lung. There was mineral dusts deposited in the bronchial mucosa may pro- no evidence of local lymphadenopathy that may compress voke a local in¯ammatory reaction with ®brosis.8,9 In our or invade into the bronchi. Bronchoscopy showed stenosis study, microscopic examination of the bronchial mucosa of the ori®ces of RML bronchus and anterior segment of reveals extensive collections of anthracotic pigment±laden right upper lobe bronchus by in¯amed mucosa with an- macrophages in the lamina propria beneath the basement thracotic pigmentation. Bronchial biopsy was performed membrane of the respiratory epithelium. Scattered lym- over the right upper lobe bronchus. Bronchial brush cy- phocytes are intermixed with dust-laden macrophages. Fi- tologic test results and acid-fast staining were nonreveal- brosis is also noted (Figure 2). Under the polarizing mi- ing. The results of 2 sputum cultures for AFB were also croscope, there are numerous needle-shaped birefringent negative. Chest x-ray ®lms showed no signi®cant change crystals of silica-like particles in the macrophages and after 16 months of follow-up. within the cleftlike space between the collagenous stroma The results of clinical studies are summarized in the (Figure 3, a and b).