Inert Dusts/Hard metal pneumoconiosis:
Clinical:
Accumulation of non-fibrogenic dusts may also produce pulmonary parenchymal abnormalities. Particles are deposited at the end of conducting airways at their junction with the respiratory bronchioles. Conglomerations of these particles are radio-opaque, but there is no associated inflammatory response or fibrosis. Generally, these patients feel healthy and have no functional impairment, despite horrible looking chest radiographs. Some offending agents are iron (siderosis- electric arc and oxyacetylene welders may inhale finely divided particles of iron oxide), tin (stannosis), barium (baritosis), and antimony (antimony pneumoconiosis).
Siderosis occurs secondary to accumulation of iron oxide within pulmonary macrophages [2]. Due to admixture of the inhaled iron with silica, patients can develop silicosiderosis which may be associated with pulmonary fibrosis [2]. Typical radiographic findings include small nodules which are most prominent in the perihilar, middle third of the lungs [2]. HRCT shows small ill-defined centrilobular nodules (71% of patients) with or without fine branching structures (which indicate the deposition of minute iron oxide particles along perivascular and peribronchial lymphatic vessels [2]. Other findings include ground glass opacities, reticulation, and areas of high attenuation indicating organizing pneumonia with siderosis [2].
X-ray:
In general, CXR findings in patients with heavy metal pneumoconiosis typically demonstrate the presence of micronodules (small rounded opacities) which can mimic silicosis, but are most prominent in the perihilar regions. These changes are reversible and can resolve after exposure ceases. These nodules do not represent reactive fibrosis, but rather radiopaque accumulations of particles that lie within macrophages aggregated along the perivascular and peribronchial lymphatics.
HRCT will demonstrate the presence of ill-defined centrilobular micronodules [1]. Other findings include ground glass opacities
REFERENCES:
(1) Radiographics 2001; Kim KI, et al. Imaging of occupational lung disease. 21: 1371-1391
(2) Radiographics 2006; Chong S, et al. Pneumoconiosis: comparison of imaging and pathologic findings. 26: 59-77
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
