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Etymology

  • Derived from “calcified,” indicating the deposition of calcium salts, and “lymph nodes,” referring to the lymphatic organs that filter lymph fluid and participate in immune responses.

AKA and abbreviation

  • No commonly accepted abbreviation.

What is it?

  • Calcified lymph nodes in the chest refer to thoracic lymph nodes that have undergone calcification, often visible on imaging as areas of increased density.
  • Calcification typically indicates a prior or chronic process, such as granulomatous infection, malignancy, or other metabolic or inflammatory conditions.

Characterized by

  • Calcification patterns on imaging:
    • Central calcifications: Common in healed granulomatous infections such as tuberculosis or histoplasmosis.
    • Eccentric calcifications: Seen in metastatic lymphadenopathy or post-radiation therapy.
    • Eggshell calcifications: Thin peripheral calcifications, characteristic of silicosis or sarcoidosis.
    • Lobulated calcifications: Associated with conditions like Castleman disease or amyloidosis.
    • Psammommatous calcifications: Lamellated, round calcifications seen in metastases from papillary thyroid carcinoma or mucinous adenocarcinomas.
  • Associated findings:
    • Enlarged lymph nodes with or without calcifications, depending on the chronicity and etiology of the underlying condition.
    • Surrounding lung changes, such as fibrosis, ground-glass opacity, or pleural thickening.

Anatomical Context

  • Thoracic lymph nodes typically affected:
    • Mediastinal nodes: Paratracheal, subcarinal, and para-aortic nodes.
    • Hilar nodes: Located at the lung hila near pulmonary arteries and bronchi.
    • Intrapulmonary nodes: Within the lung parenchyma near bronchi or pulmonary arteries.

Caused by

Most common cause: Healed granulomatous infections such as tuberculosis or histoplasmosis.

Other causes include:

  • Infections:
    • Chronic fungal infections (e.g., histoplasmosis, coccidioidomycosis).
    • Healed tuberculosis with residual calcifications.
  • Inflammatory/Immune:
    • Sarcoidosis, often associated with bilateral hilar lymphadenopathy and eggshell calcifications.
    • Silicosis, classically presenting with eggshell calcification.
  • Neoplasm:
    • Calcified metastases from papillary thyroid carcinoma or mucinous adenocarcinomas (psammommatous calcifications).
    • Hodgkin’s lymphoma post-treatment.
  • Metabolic:
    • Amyloidosis with lobulated or irregular calcifications in affected nodes.
  • Other:
    • Castleman disease, characterized by lymph node enlargement with lobulated calcifications.
    • Post-radiation therapy changes.

Resulting in

  • Limited functional impact unless nodes are significantly enlarged or associated with other processes, such as fibrosis or airway obstruction.

Structural changes

  • Deposition of calcium within the nodal tissue.
  • May coexist with fibrosis or necrosis, depending on the underlying cause.

Pathophysiology

  • Calcification occurs as a late stage of healing or chronic inflammation, often due to macrophage activity in granulomatous diseases or metastatic calcification from systemic conditions.
  • Chronic infections and immune responses lead to dystrophic calcification within lymph nodes.

Pathology

  • Granulomatous diseases: Dense calcium deposits within nodal granulomas.
  • Neoplastic diseases: Focal or diffuse calcification within malignant or metastatic nodes.
  • Amyloidosis: Calcifications associated with proteinaceous deposits in the lymph nodes.

Diagnosis

  • Clinical correlation: Often asymptomatic but may present with signs of the underlying disease (e.g., cough, dyspnea, fever).
  • Imaging:
    • CXR: Visible as high-density opacities in characteristic nodal locations.
    • CT: Provides detailed characterization of calcification patterns and associated findings.

Clinical

  • Symptoms:
    • Asymptomatic in most cases.
    • Symptoms are usually related to the underlying cause, such as pulmonary infection or sarcoidosis.
  • Signs:
    • Systemic signs like fever, weight loss, or fatigue in infectious or malignant conditions.

Radiology Detail

CXR:

  • Findings: Dense opacities in mediastinal, hilar, or intrapulmonary regions.
  • Associated Findings: Fibrosis, pleural thickening, or associated lung changes.

CT:

  • Parts: Mediastinal, hilar, and intrapulmonary lymph nodes.
  • Size: Calcification may occur in normal or enlarged nodes.
  • Shape: Rounded, lobulated, or irregular, depending on the etiology.
  • Position: Central, peripheral, or random within the lymph node.
  • Character:
    • Calcifications: Central, eccentric, eggshell, psammommatous, or lobulated.
    • Associated low-density areas may indicate necrosis or cystic degeneration.
  • Associated Findings: Surrounding fibrosis, lung opacities, or pleural changes.

Other relevant Imaging Modalities:

  • MRI: Limited utility but can identify associated soft-tissue changes.
  • PET-CT: Typically shows low metabolic activity in benign calcified nodes but may help differentiate from malignant causes.

Pulmonary function tests (PFTs)

  • Usually normal unless nodes are associated with airway compression or parenchymal fibrosis.

Recommendations

  • Evaluate calcification patterns in conjunction with clinical history and other imaging findings.
  • Monitor for progression if associated with chronic conditions like sarcoidosis.
  • Biopsy may be required if malignancy or unusual pathology is suspected.

Key Points and Pearls

  • Calcified lymph nodes in the chest are commonly due to healed granulomatous infections like tuberculosis or histoplasmosis.
  • Characteristic calcification patterns (e.g., eggshell, psammommatous, eccentric) help narrow the differential diagnosis.
  • PET-CT can differentiate benign calcifications (low metabolic activity) from malignant causes (increased uptake).
  • Sarcoidosis and silicosis are classic causes of eggshell calcifications, whereas psammommatous calcifications are associated with papillary thyroid carcinoma and mucinous adenocarcinomas.