High-Attenuation Mass, Mediastinum or Hilum

Jud W. Gurney, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Calcified Lymphadenopathy
- Histoplasmosis
- Tuberculosis
- Pneumocystis Pneumonia
- Mediastinal Fibrosis
Goiter
Aneurysm
Hematoma

Less Common

Silicosis/Coal Worker’s Pneumoconiosis
Neoplastic
- Treated Hodgkin Lymphoma
- Thymoma
- Teratoma
- Neuroblastoma
- Castleman Disease
- Metastases
Sarcoidosis

Rare but Important

Amyloidosis
Foregut Cyst
Hemangiomas
Gossypiboma
Aluminum Pneumoconiosis
Perflubron Ventilation

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Mnemonic: EGGSHELL CA⁺
- Environmental dusts (silica, coal, aluminum)
- Goiter
- Gossypiboma
- Sarcoidosis
- Hemangioma
- Ecchymosis (hematoma)
- Lymphoma (treated Hodgkin)
- Lymph nodes (histoplasmosis, tuberculosis, PCP)
- Cancer (thymoma, teratoma, neuroblastoma, metastases, or Castleman)
- Aneurysm

Helpful Clues for Common Diagnoses

Calcified Lymphadenopathy
- Histoplasmosis
  - Calcification of granuloma and nodes age and time dependent
  - Calcification within months in children, years in adults
  - Either central nidus or diffuse calcification pattern
  - Nodes follow drainage pattern of lung granuloma
  - Splenic calcification common
  - Multiple small pulmonary calcifications in histoplasmosis; fewer, larger pulmonary calcifications in tuberculosis
- Tuberculosis
  - Nodal calcification often diffuse
  - Seen in 50%
- Mediastinal Fibrosis
  - Focal mediastinal mass > 5 cm diameter, most common paratracheal
  - Central calcification in mass (90%), also seen in peripheral granuloma
  - Eventually obstructs superior vena cava, airways, & pulmonary veins, in that order
Goiter
- Calcification: Coarse, punctate, or rings
Aneurysm
- Curvilinear calcification
- Due to atherosclerosis, trauma, fungal infection, cystic medial necrosis, vasculitis
Hematoma
- Acute hematoma due to trauma, catheter insertion, surgery, clotting disorder, aneurysms, tumor
  - Consider ectopic parathyroid adenoma, which may spontaneously hemorrhage
- 90% of clots have ↑ attenuation over 1st 72 hours

Helpful Clues for Less Common Diagnoses

Silicosis/Coal Worker’s Pneumoconiosis
- Eggshell calcification in 3-6%
- Associated with interstitial lung disease
Neoplastic
- Treated Hodgkin Lymphoma
  - Following radiation therapy, ˜ 20% of nodal masses will calcify
  - 2 types: Eggshell or multiple discrete deposits (mulberry type)
  - Extremely rare (case reports) of calcification prior to treatment
- Thymoma
  - 1/3 have calcification: Thin linear in capsule, scattered punctate calcification less commonly seen
  - Also seen in invasive thymomas
- Teratoma
  - a.k.a. dermoid cyst
  - Teratomas: 70% of germ cell tumors
  - Fat: 75%, fluid: 90%, calcification: 40%
  - Calcification may have tooth shape
- Neuroblastoma
  - Calcification (80%): Cloud-like, stippled, ring-shaped, solid
- Castleman Disease
  - Calcification (5-10%): Discrete, coarse, or tree-like, rarely visible on radiographs
- Metastases
  - Usually seen in those with known disease
  - Osteosarcoma, mucinous colon or ovarian, papillary thyroid carcinoma most common tumors
Sarcoidosis
- 50% have calcification, 40% within 1 year of diagnosis
- Calcification typically central: Smudgy or putty-like, may be eggshell but uncommon

Helpful Clues for Rare Diagnoses

Amyloidosis
- Adenopathy, isolated or associated with interstitial lung disease (50%)
- Usually multiple lymph node groups, may be massive
- Calcification stippled, diffuse, or eggshell
- Systemic disease common, typically Waldenström macroglobulinemia
Foregut Cyst
- Bronchogenic cysts most common (50%)
- Calcification either in fluid (milk of calcium: 3%), less common curvilinear in wall
Hemangiomas
- Phleboliths: 10-40% (fat 40%)
  - Central area of decreased attenuation pathognomonic for phlebolith (in 7%)
  - More common: Multiple punctate round calcifications (30%)
Gossypiboma
- Retained surgical sponge or swab
- Spongiform low-density mass with gas bubbles
- Sponges in USA contain radiopaque markers, often 1 or 2 linear wires
- Calcification also deposited along network architecture of surgical sponge (“calcified reticulate rind”)
Aluminum Pneumoconiosis
- Nodes with diffuse homogeneous increased attenuation (from aluminum)
Perflubron Ventilation
- Used in severe respiratory failure
- Contains bromine atoms, which makes agent radiopaque
- May accumulate and remain long term in lymph nodes and efface mediastinal fat

Image Gallery

Frontal radiograph shows multiple small, peripheral, discrete, calcified granulomas

and multiple enlarged, calcified hilar and mediastinal lymph nodes

from histoplasmosis.

Axial CECT shows multiple calcified hilar and mediastinal lymph nodes in a patient with previous pneumocystitis pneumonia. Nodes are either diffusely calcified

or show eggshell calcification

(Left) Coronal NECT reconstruction shows a large subcarinal calcified mediastinal mass

narrowing the right main bronchus

. Subcarinal location is the 2nd most common location. Typically fibrosis in this area obstructs airways or pulmonary veins. (Right) Axial CECT shows a large superior mediastinal mass