CT–Pathology Comparisons

Multiple nodules or masses on thin-section CT are related to the proliferation of tumor cells within the interstitium and extension of tumor cells into the parenchymal interstitium and airspaces.

Patient Prognosis

Patients with pulmonary marginal zone B-cell lymphoma usually have limited disease and follow an indolent clinical course with favorable response. Diffuse large B-cell lymphomas are aggressive, but complete remission and long-term survival can be seen, with reported survival time of approximately 8Ð10 years [15].

Pulmonary Epithelioid

Hemangioendothelioma

Pathology and Pathogenesis

Pulmonary EH in the lung reveals single or multiple nodules replacing normal lung architecture (Fig. 19.4). These nodules display different stages of development; some show areas of calciÞcation and ossiÞcation, while others show a characteristic chondromyxoid background, and still others may show a predominant solid cellular proliferation. Polypoid nodules are arranged within alveolar spaces or are seen inÞltrating into interstitial areas. At higher magniÞcation, the tumor cells are seen to be arranged in small nests or cords within the myxoid background (Fig. 19.2). Although necrosis may be seen in a few cases, mitotic activity and cellular pleomorphism are unusual [16, 17].

Symptoms and Signs

Pulmonary EH is diagnosed incidentally in about half of the patients [18]. Respiratory symptoms including cough, dyspnea, hemoptysis, and chest pain has been described. Weight loss can be seen.

CT Findings

The most common CT Þnding of pulmonary EH is the presence of multiple discrete nodules [16, 17] (Fig. 19.4). The nodules range in size up to 2 cm, but most are less than 1 cm in diameter. On serial CT examinations, these lesions

have little or no growth. Other Þndings of pulmonary EH include multiple reticulonodular opacities mimicking hematolymphangitic metastasis and diffuse inÞltrative pleural thickening mimicking malignant pleural mesothelioma or diffuse pleural carcinomatosis [19, 20].

CT–Pathology Comparisons

The tumor cells of pulmonary EH typically spread into adjacent bronchioles and alveolar spaces in a micropolypoid manner, resulting in multiple nodules on CT scans (Fig. 19.4). InÞltrative nodular proliferation of tumor cells within the lumina of small arteries, veins and lymphatics might simulate hematolymphangitic metastases and inÞltrative growth pattern of epithelioid tumor cells along the pleura could mimic diffuse malignant pleural mesothelioma [16].

Patient Prognosis

Surgery can be proposed in cases of unilateral single or multiple nodules. There is no single effective treatment in cases of bilateral multiple nodules. The 5-year survival probability is 60 % (range, 47Ð71 %). Patients with hemorrhagic symptoms and pleural effusion show a worse survival.

Amyloidomas

Pathology and Pathogenesis

Amyloidosis is the extracellular deposition of misfolded proteins in beta-pleated sheets. Amyloidoma is nodular amyloidosis, which presents as single or multiple nodules measuring 1Ð4 cm in diameter (Fig. 19.5). These are Þrm, irregular, and yellow to gray. Histologically, amyloid is amorphous eosinophilic material with a foreign-body giant cell reaction. That may have lymphoplasmacytic inÞltrate at the periphery of the nodules, calciÞcation, chondriÞcation, or ossiÞcation. Please also note section ÒHoneycombing with Upper Lung Zone PredominanceÓ in Chap. 17.

Symptoms and Signs

Amyloid nodules in the lung parenchyma are usually an incidental Þnding that need to be distinguished from neoplasia [21]. Larger nodules can occasionally produce spaceoccupying effects.