The patient worked as an accountant in a restaurant when she was 19 years old for 8 years, as a bottler in a mineral water company for 4 years, and as a housewife for the next 4 years. Then she was engaged in attaching labels to fishing rods in a factory from 2007 to 2016. She had no occupational dust or fume exposure during these three early careers. From 6th July 2016 to 8th Oct 2018, the patient was engaged in polishing snowboards at a sporting products company. She worked 5-6 days per week and 8-12 h per day, using white corundum electric grinding wheels to polish the polyethylene baseplate of snowboards. It was a wet process with water-soluble cutting fluid spraying on the electric grinding wheels. The chief constituents of water-soluble cutting fluid were polyether, lauric acid, amine, and 1H-benzotriazole. She wore dust respirators during the operation. The workplace was ~2,000 m2 with 12 production assembly lines. There were four grinding machines with eight electric grinding wheels in every assembly line. The patient and four colleagues worked together on the same assembly line, using 30 grinding wheels each month, each weighing 10 kg. None of her 106 colleagues in the same workplace reported similar symptoms and their chest radiographs of regular occupational medical check-ups were all normal.
The level of air dust in the workplace from 2016 to 2018 was detected. Exposure concentration of time-weighted average (CTWA) and short-term (CSTEL) of mixed dust in a different spot of the workplace was 1.05-8 times the occupational exposure limits (OELs) in 2016 and 2017, while the concentration of polyethylene dust was within the OELs. The maximum CTWA and CSTEL of mixed dust were 57.5 and 55.7 mg/m3, respectively, exceeding the permissible concentration-time weighted average (8 mg/m3) by seven times. Elemental analysis was performed on the grinding wheel powder in the workplace by an X-ray fluorescence spectrometric analyzer. The assay showed that 72.7% of Al2O3 and 22.8% of SiO2 were raw materials. The water-soluble cutting fluid was detected. Microorganism stains and cultures, such as bacteria, acid-fast bacilli, and fungi, were negative.
The patient resigned from her job. She was diagnosed with pneumoconiosis at a local occupational hospital and received oral prednisone with a dosage of 0.5 mg/kg/day for 2 weeks. The dosage was gradually tapered to 5 mg/day for a total of 36 weeks (Figure 2). The discontinuation of occupational exposure and the first course of using corticosteroids resulted in an improvement of symptoms and a slight reduction of the multiple nodules in lung fields (Figures 2C, D). In November 2019, after the cessation of oral prednisone for 3 months, the symptoms worsened, her lung function value of DLco (Figure 2) was significantly reduced to 50%, and findings on the chest CT (Figures 2E, F) were more severe than before. She received oral prednisone again with an initial dosage of 15 mg/day from 23 April 2020. The dosage was gradually tapered to 5 mg/day (Figure 2). The respiratory symptoms were improved. She was then admitted to our hospital for further medical evaluation on 3 Nov 2020. The patient had no history of other diseases. She was a non-smoker and denied having tuberculosis, night sweats, fever, chills, or weight loss previously.
Physical examination revealed chest roughness on auscultation. The remaining clinical examination was without particularity, and no extrathoracic signs or symptoms such as arthralgia, myalgia, dry eye, or dry mouth syndrome were found. The patient had no history of asthma, allergies, or any family history of respiratory disorders. Her lung function was almost improved to the initial level, with FVC of 3.15 L (110% predicted) and DLco of 62.3% predicted (Figure 2) after the second course of using prednisone in the local hospital. HRCT revealed multiple ill-defined centrilobular nodules and patchy GGOs gradually reduced with oral prednisone therapy (Figures 2G, H). Neither evidence of pleural fluid nor cardiac enlargement was noted. A video-assisted thoracoscopic surgery (VATS) biopsy of the right lower lobe was performed for further examination. The histological appearance under the microscope showed many well-formed non-necrotizing granulomas composed of epithelioid and multinucleated giant cells, mainly around the bronchi and vessels, with fibrous hyperplasia and lymphocytic inflammation (Figures 3A, B); a Schaumann body was also observed (arrows) (Figure 3C). Lightly pigmented dust macules within the interstitium were observed with adjacent focal emphysema. No classic silicotic nodules were detected. Microorganism stains and cultures, including acid-fast bacilli and fungi, were negative. In addition, 122.55 mug/g of aluminum and 455.23 mug/g of silicon were detected in the lung tissue by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma emission spectrometer (ICP-AES). No tungsten, cobalt, or beryllium was detected in both grinding wheel powder or biopsy samples.
Based on occupational dust exposure combined with clinical, radiological, and histological findings of sarcoid-like granulomatosis, the patient was diagnosed with aluminum-associated sarcoid-like granulomatous lung disease by a multidisciplinary panel, rather than sarcoidosis. Upon admission to our hospital in November 2020, the respiratory symptoms, chest HRCT scans, and lung function of DLco improved; therefore, the second course of prednisone therapy lasted for a total of ~ 28 weeks. She was administered oral N-acetylcysteine and inhalational corticosteroids. After discharge from our hospital, she was followed up regularly in a local occupational hospital. During the 36-month follow-up observational period, her chest CT (Figures 2I, J) revealed that GGOs slightly increased, and fiber streak shadows were observed in the lower lobe of the right lung, as well as the value of DLco reduced to 54%; however, her respiratory symptoms were stable. A 48-month follow-up revealed that her symptoms of dyspnea on exertion gradually worsened, while GGOs (Figures 2K, L) gradually increased and DLco reduced to 46%. The patient gained weight significantly after oral glucocorticoid treatment. After stopping the glucocorticoid, the shortness of breath was not obvious in the resting state, so she resisted the use of glucocorticoid therapy again.
This study was approved by the Medical Ethical Committee and the patient provided informed consent for the publication of the case.