What types of cancers can cause miliary nodules?

From the Guidelines

Miliary nodules can be caused by several types of cancers, with thyroid cancer being a notable example, as shown in a CT image from the Fleischner Society 2017 guidelines 1. The most common cancers that cause miliary nodules include:

• Thyroid cancer, as evidenced by a CT image showing multiple solid nodules of varying size with lower zone predominance secondary to metastatic thyroid carcinoma 1
• Renal cell carcinoma
• Melanoma
• Breast cancer
• Colorectal cancer These cancers can spread hematogenously to the lungs, resulting in multiple small nodules that have a millet seed-like appearance on chest imaging, typically 1-3 mm in size and diffusely distributed throughout both lungs. Other malignancies that can occasionally present with miliary patterns include:
• Pancreatic cancer
• Testicular cancer
• Certain sarcomas It's essential to note that while cancer is a significant cause of miliary nodules, other conditions like tuberculosis, fungal infections, sarcoidosis, and pneumoconiosis can also produce similar radiographic patterns. When miliary nodules are identified, a comprehensive diagnostic workup including imaging studies, laboratory tests, and often tissue biopsy is necessary to determine the underlying cause, as the distribution of nodules and their size can guide management, particularly when the distribution has peripheral and/or lower zone predominance and when the size of the nodules has a wide range 1.

From the Research

Types of Cancers that Cause Miliary Nodules

• Miliary nodules can be caused by various types of cancers, including:
  • Thyroid cancer: Pulmonary metastases from thyroid cancer can present with a micronodular or miliary pattern throughout both lungs 2
  • Extrathoracic malignancy: Miliary nodules can occur in patients with extrathoracic malignancies, as seen in a study where 5 out of 53 patients with miliary nodules had extrathoracic malignancy 3
  • Primary lung cancer: Although rare, primary lung cancer can also cause miliary nodules, as reported in a study where 1 out of 53 patients with miliary nodules had primary lung cancer 3

Characteristics of Miliary Nodules in Cancer Patients

• Miliary nodules in cancer patients can have different characteristics, such as:
  • Micronodular pattern: Pulmonary metastases from thyroid cancer can present with a micronodular pattern throughout both lungs 2
  • Random presentation: High-resolution computed tomography findings can show a random presentation of miliary nodules in relation to the secondary lobule 4

Diagnosis and Treatment of Miliary Nodules in Cancer Patients

• Diagnosis of miliary nodules in cancer patients can be made using:
  • High-resolution computed tomography: This imaging modality can help identify the characteristics of miliary nodules and aid in differential diagnosis 4
  • Fine-needle aspiration biopsy: This diagnostic tool can be used to diagnose thyroid cancer, which can cause miliary nodules 5
• Treatment of miliary nodules in cancer patients can include:
  • Surgical intervention: Total thyroidectomy can be recommended for patients with follicular carcinomas and papillary carcinomas > 1.0 cm 5
  • Radioactive iodine: This treatment can be used to increase disease-free interval and survival in patients with well-differentiated thyroid carcinoma 6