Diagnosis: Hematolymphangitic Metastasis in a colon cancer patient
 

Radiologic Findings

Chest radiograph shows diffuse reticulonodular opacities in association with several large nodules in both lungs. Right paratracheal widening is observed. Mediastinal window setting images of high-resolution CT scan show multiple enlarged mediastinal lymph nodes. Punctate or amorphous calcifications are identified in the enlarged lymph nodes. Lung window setting images of HRCT scan shows nodular thickenings of interlobular septa, peribronchovascular interstitium and interlobar fissures in both lungs. There are several nodules in RML & lingular segment, showing pseudocavitations (bubblelike areas of low attenuation).

 

Brief Review

Pulmonary lymphangitic carcinomatosis (PLC) occurs commonly in patients with metastatic adenocarcinomas from the breast, lung, stomach, colon, pancreas, or cervix. PLC usually results from hematogenous spread to lung, with subsequent interstitial and lymphatic invasion, but can also occur because of direct lymphatic spread of tumor from mediastinal and hilar lymph nodes. Tumor growth in the lymphatics in peribronchovascular interstitium, interlobular septa and subpleural regions, and associated edema, result in characteristic HRCT findings of smooth or nodular interstitial thickenings with preservation of normal lung architecture. Diseases showing smooth (pulmonary edema) or nodular interstitial thickenings (sarcoidosis or silicosis) should be included in differential diagnosis.  Calcified mediastinal or hilar lymph nodes are most frequently identified in patients with granulomatous disease such as tuberculosis or histoplasmosis. In this entity, lymph nodes are usually diffusely calcified. Calcified lymph nodes may also be seen in patients with sarcoidosis, silicosis or coal worker's pneumoconiosis, Hodgkin's disease following preceding radiation, amyloidosis, scleroderma, Castleman's disease and in AIDS patients with pneumocystis carinii infection. Rarely, calcification may occur within nodes as a result of metastatic disease, typically from the colon.  Pseudocavitation (bubblelike areas of low attenuation within a nodule) is one of characteristic findings of nodular form of bronchioloalveolar carcinoma (BAC), a subtype of adenocarcinoma. Diagnosis of BAC can be made in patients who do not have other bronchogenic adenocarcinoma nor adenocarcinoma involving another organ, because metastatic adenocarcinoma from colon, pancreas, or biliary tract with growth along the alveolar septa may mimic BAC histologically. Metastatic adenocarcinoma may also shows radiologic findings similar to bronchioloalveolar carcinoma.

 

References

1. Munk PL, Muller NL, Miller RR, Ostrow DN. Pulmonary lymphangitic carcinomatosis: CT and pathologic findings. Radiology 1988; 166:705-709 .2. Mediastinum. In Naidich DP, Zerhouni EA, Siegelman SS. Computed tomography and magnetic resonance of the thorax. 2nd ed. New York: Raven Press, 1991:35-148 3. Lee KS, Kim Y, Han J, Ko, EJ, Park CK, Primack SL. Bronchioloalveolar carcinoma: clinical, histopathologic, and radiologic findings. Radiographics 1997;17:1345-1357

A Letter from Dr. Kyung Soo Lee, Editor of the Website.

Dear Dr. Kim:
 
This is a very tough case to make a diagnosis. The patient, 41-year-old woman, complained of progressive dyspnea
with palpable and probable supraclavicular lymph nodes.
 
Chest radiograph shows small nodular or reticulonodular lesions in both lungs, especially in middle and lower lung zones.
Widening and increased density are noted in right paratracheal area, suggesting paratracheal lymph node enlargement.
CT scan confirms the calcified lymph nodes in the right paratracheal region.
Thin-section CT shows small nodular lesions with so-called perilymphatic distribution
(nodules in the subpleural and subfissural areas as well as centrilobular regions, in addition,
nodularity of bronchovascular bundles, axial interstitium).
Tree-in-bud appearances are also seen in the lower lung zones.
Somewhat larger nodules, more than 10 mm in diameter, are also seen in the lower lung zone.
Therefore, CT images suggest mixed perilymphatic and centrilobular lesions.
What kinds of disease can result in these findings?
 
Perilymphatic distribution can be seen in sarcoidosis, pneumoconiosis, amyloidosis, and lymphangitic carcinomatosis.
Sarcoidosis may appear with both perilymphatic and centrilobular (actually it is pseudocentrilobular),
but is not likely because the mediastinal nodes show diffuse calcification.
It is very unusual that mediastinal nodes in sarcoidosis show calcification.
Usually the nodes show homogeneity with some enhancement.
Pneumoconiosis is also not likely because the disease shows predominantly middle and lower lung zone predominance.
Alveoloseptal amyloidosis may show similar findings, but diffuse calcification in mediastinal nodes may preclude the diagnosis.
Lymphangitic metastasis may be the diagnosis. However, how we can explain tree-in-bud appearances in the lower lung zone?
If the patient had vascular tumor emboli also, the findings of combined perilymphatic and perivascular distribution
of the nodules can be explained [1, 2]. How about calcification?
It may result from metastasis of mucin producing adenocarcinoma, such as colon cancer.
 
Because the profusion of the small nodules is patchy, I don't think the distribution of the nodules are random
(include miliary tuberculosis and miliary metastasis).
I don't think the nodules represent small airway disease because air trapping is not clear.
 
Conclusively the case may represent the cases of lymphangitic metastasis with vascular tumor emboli
(from mucin-producing adenocarcinoma).
Transbronchial lung biopsy may confirm the diagnosis.
 
1. Lee KS, Kim TS, Han J, et al. Diffuse micronodular lung disease: HRCT and pathologic findings.
J Comput Assist Tomogr 1999;23:99-106

2. Gruden JF, Webb WR, Naidich DP, McGuiness G. Multinodular disease: anatomic localization at thin-section CT -
multireader evaluation of a simple algorithm. Radiology 1999;210:711-720
 
With best wishes.
 
Kyung Soo Lee, MD

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