Lymphangitic carcinomatosis, or lymphangitis carcinomatosa, is the term given to tumour spread through the lymphatics of the lung, and is most commonly seen secondary to adenocarcinoma.
The demographics will reflect that of the underlying malignancy (see below).
Clinical presentation is variable. Some patients experience dyspnoea and abnormal pulmonary function tests early in the course of the disease, well before any radiographic abnormalities are evident, whereas others remain asymptomatic until much later 4.
Lymphangitis carcinomatosa is most commonly seen secondary to adenocarcinomas such as:
- breast cancer - most common 3
- lung cancer (bronchogenic adenocarcinoma)
- colon cancer
- stomach cancer
- prostate cancer
- cervical cancer
- thyroid cancer
A helpful mnemonic for lymphangitic carcinomatosis is sometimes used for its common causes.
Spread into the lymphatics in most cases (except in bronchogenic adenocarcinoma) usually occurs following haematogenous seeding of the lungs, with subsequent lymphatic involvement 1, 3. It may also occur by retrograde spread into lymphatics from the mediastinal and hilar lymph nodes.
Both the peripheral lymphatics coursing in the interlobular septa and beneath the pleura, and the central lymphatics coursing in the bronchovascular interstitium are involved 2.
Histologically tumour is seen both within lymphatics and in the adjacent interstitium, with associated oedema and desmoplasia 3, 4.
Radiographic appearances can most easily be divided into those due to involvement of the peripheral (interlobular septae) and central lymphatic system. Involvement may be diffusely of both, or predominantly of one or other compartment 4. Distribution of changes is variable, but most are asymmetric and patchy 3. It is usually bilateral but may be unilateral especially in cases of lung and breast cancer.
Unfortunately up to a quarter of patients with subsequently established lymphangitic carcinomatosis have normal chest x-rays 2. When abnormal the most common finding is of a reticulonodular pattern, with thickening of the interlobular septae which may resemble Kerley B lines.
CT, especially HRCT, is excellent at demonstrating both peripheral and central changes.
Typically the appearance is that of interlobular septal thickening most often nodular and irregular, although smooth thickening may also sometimes be seen 1-4. This results in prominent definition of the secondary pulmonary lobules, manifesting as tessellating polygons.
Thickening of the bronchovascular interstitium is usually irregular and nodular, with changes seen extending towards the hilum 4.
The combination may give a characteristic "dot in box" appearance.
Additional HRCT findings include 2, 4:
- subpleural nodules, and thickening on the interlobar fissures
- pleural effusion(s): pleural carcinomatosis
- hilar and mediastinal nodal enlargement (40-50%)
- relatively little destruction of overall lung architecture
A helpful sign is that the overall lung and lobular architecture is preserved 1. In most cases, lymphangitic carcinomatosis progresses rapidly and patients deteriorate (see treatment and prognosis below), however in some cases changes may remain stable over considerable time 3. As such a 'stable' appearance when compared to previous imaging does not necessarily exclude the diagnosis.
Treatment and prognosis
Treatment is determined by the histology of the primary tumour, but in general relies on systemic chemotherapy.
Prognosis of patients with lymphangitic carcinomatosis is poor, with approximately half of patients having succumbed to their illness within a year of diagnosis 2, 3. Occasionally long term survival is encountered 3.
Considerations include a differential for that of thickened interlobular septae, with common entities comprising of 1, 3:
- 1. Naidich DP, Srichai MB, Krinsky GA. Computed tomography and magnetic resonance of the thorax. Lippincott Williams & Wilkins. (2007) ISBN:0781757657. Read it at Google Books - Find it at Amazon
- 2. Kazerooni EA, Gross BH. Cardiopulmonary imaging. Lippincott Williams & Wilkins. (2004) ISBN:0781736552. Read it at Google Books - Find it at Amazon
- 3. Ikezoe J, Godwin JD, Hunt KJ et-al. Pulmonary lymphangitic carcinomatosis: chronicity of radiographic findings in long-term survivors. AJR Am J Roentgenol. 1995;165 (1): 49-52. AJR Am J Roentgenol (abstract) - Pubmed citation
- 4. Johkoh T, Ikezoe J, Tomiyama N et-al. CT findings in lymphangitic carcinomatosis of the lung: correlation with histologic findings and pulmonary function tests. AJR Am J Roentgenol. 1992;158 (6): 1217-22. AJR Am J Roentgenol (abstract) - Pubmed citation