MyPACS.net: Radiology Teaching Files > Case 57720434

Last visited 12/14/2011 NODULAR OPACITIES ON CXR
Contributed by: Matthew Minor, Resident, Wilford Hall Medical Center, Texas, USA.
Patient: 62 year old male
History: 62 year old male presented with atypical chest pain.
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Findings:

Radiographs:

-Innumerable small bilateral nodular radiodensities project over the bilateral lungs.

CT:

-No axillary, supraclavicular, mediastinal, or hilar lymphadenopathy.

-No pathologically enlarged hilar or mediastinal lymph nodes noted.

-There are multiple small calcified pulmonary nodules seen, which are too numerous to count.

-No evidence of pneumothorax or focal consolidation. No pleural effusions. Posterior pleural fat is noted.

Diagnosis: Granulomatous Disease
Discussion:

Calcified pulmonary nodules are a specific group of hyperdense nodules that can be easily differentiated on CT but may be difficult to detect on plain radiographs if less than 5 mm or pleural based. The most common cause of calcified nodules is granuloma formation, as a sequela of prior infection; however several other etiologies exist.  This includes but is not strictly limited to the following: inhational lung disease (pneumoconiosis), metastatic calcification (pulmonary sarcoidosis), pulmonary hemosiderosis, pulmonary alveolar microlithiasis.

In the determination of malignant versus benign etiologies, there are a few stereotypical characteristics that may be useful in determining which is more likely.  These are not strict characteristics and may not always be applicable.

  1. Multiple pulmonary nodules ≥1 cm in diameter or detected by radiography are likely due to metastatic disease.
  2. Multiple pulmonary nodules <5 mm in diameter, juxtaposed to either the visceral pleura or an interlobar fissure, are more likely to be benign lesions.
  3. In patients with known malignancy, multiple pulmonary nodules that are larger than 0.5 cm in diameter are more likely to be malignant than benign.

Malignant Diseases — Nodules secondary to metastatic disease may vary in size and location. There appears to be a higher incidence of nodules within the lung bases and sub-pleural. Metastatic lesions are usually round with sharply demarcated borders, but metastases that tend to hemorrhage (e.g., choriocarcinoma, renal cell carcinoma, melanoma, thyroid carcinoma, Kaposi's sarcoma) may have indistinct, fuzzy borders. Cavitation is an uncommon characteristic of malignant nodules but may be seen with squamous cell carcinoma.

Non-Hodgkin lymphoma can occasionally manifest with multiple pulmonary nodules. Such nodules usually originate from bronchial-associated lymphoid tissue (BALT). They have a bias for the lower lobes and occasionally are surrounded by a halo of ground glass attenuation or contain air bronchograms. Enlarged mediastinal or hilar lymph nodes may not be present, particularly if the lymphoma has recurred outside of a previously irradiated portal. Multiple peribronchovascular pulmonary nodules may be a manifestation of Kaposi's sarcoma in an HIV+ patient. The size of the nodules may exceed 1 cm.

Benign Diseases — Benign diseases associated with multiple pulmonary nodules include infections, non-infectious inflammatory conditions, arteriovenous malformations, and pneumoconioses.

Multiple pulmonary nodules may be sequela of an number of fungal infections to include aspergillosis, histoplasmosis, coccidioidomycosis, and cryptococcosis. Nodules due to fungal infection tend to have a wide variation in diameter (0.5 to 3 cm) without a predilection for a specific area of the lungs. With invasive aspergillosis, nodules are the predominant finding.  A surrounding halo of ground glass attenuation due to local hemorrhage (halo sign) is often seen. Infrequently do these infections progress to cavitation, creating a "crescent-sign". Histoplasmosis nodules may remain unchanged in size for many years and may display calcification. Cryptococcus can produce multiple subcentimeter nodules or larger nodules/masses in patients with HIV and less likely in immunocompetent patients.

Tuberculosis and atypical mycobacterial infections can yield multiple nodules, which are larger than the miliary micronodules that are characteristic for hematogenous dissemination. These macronodules exceed 5 mm in diameter and may be the result of endobronchial spread of disease, with a predominance to the upper lobes and in the superior segment of the lower lobes. Overall, multiple nodules caused by mycobacterial infections are relatively rare in comparison to the other characteristic imaging manifestations of tuberculosis and atypical mycobacterial infections.

Multiple pulmonary nodules may result from a number of inflammatory conditions. The most common is granulomatosis with polyangiitis (Wegener's granulomatosis), which can produce multiple round lesions varying in size from 0.5 to 10 cm. These lesions may be poorly or well demarcated and are frequently associated with areas of consolidation. Cavitation may occur and produces a thick wall with an irregular inner contour. Multiple pulmonary nodules have also been described with rheumatoid arthritis, lymphomatoid granulomatosis, amyloidosis, and sarcoidosis, however cavitation is less likely with these diseases.

Both coal workers' pneumoconiosis and silicosis may evolve into progressive massive fibrosis or conglomerate masses, yielding multiple pulmonary nodules that range in size from 1 to 10 cm and are usually located in the upper lobes. A background pattern of small nodular opacities is usually apparent. Calcification and cavitation of these nodules are unusual; however, when they occur, superimposed tuberculosis has to be suspected. Beryllium-associated lung disease can present with multiple pulmonary nodules and mimic the radiologic appearance of sarcoidosis. Caplan’s disease is a combination of rheumatoid arthritis and pneumoconiosis that manifests multiple pulmonary nodules.

References:

Collins J, Stern EJ. Chest radiology, the essentials. Lippincott Williams & Wilkins. (2007)

www.uptodate.com

www.statdx.com

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Additional Details:

Case Number: 57720434Last Updated: 2011-12-14
Anatomy: Chest   Pathology: Infection
Modality: CT, Conventional RadiographAccess Level: Readable by all users

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