A case of pseudocystic liver metastases from an atypical lung carcinoid tumor

Abstract

Metastatic neuroendocrine tumors of the liver typically appear as solid, hypervascular masses on imaging. Pseudocysts mimicking simple cysts are extremely rare. A 42-year-old Japanese woman was referred with a single pulmonary mass in the left lower lobe. No metastatic lesion was detected and no occupying lesion in the liver was observed. The lung tumor was diagnosed as an atypical carcinoid. Postoperative investigation revealed new hepatic simple cysts in the liver, which increased in size over time and changed into hemorrhagic cysts. Fluorodeoxyglucose positron emission tomography and somatostatin receptor scintigraphy using ¹¹¹In-octreotide demonstrated no accumulation in the liver. Our patient did not have symptoms consistent with carcinoid syndrome. The patient underwent partial resection of the cystic lesions of the liver. Gross examination of the tumors demonstrated thin-wall cavitated lesions with hemorrhage which were metastases from the atypical carcinoid of the lung. When a growing cystic lesion with intracystic hemorrhage is found in the liver of a patient with a history of carcinoid tumors, pseudocysts caused by degeneration of a carcinoid metastasis should be considered as a differential diagnosis.

Keywords: Carcinoid metastasis; Liver metastasis; Lung carcinoid tumor; Neuroendocrine tumor; Pseudocyst.

Fig. 1

Chest radiograph and contrast-enhanced computed tomography (CT) of the chest obtained at the initial presentation. (a) Chest radiograph shows a solid lobulated tumor in the left lower lung field. Coronal (b) and axial (c) CT images show a 3 cm, lobulated solid tumor in the left lower lobe. Pre- (d) and post- (e) contrast-enhanced CT images show homogenous enhancement of the tumor.

Fig. 2

Histopathological examination of the lung tumor. (a) Photomicrograph (original magnification, 100×; hematoxylin and eosin staining) shows characteristic neuroendocrine morphology including nesting, cord-like pattern, rosette formation, and peripheral palisading of tumor nests. (b) The tumor is composed of polygonal and spindle cells with round and oval shaped nuclei, granular nuclear chromatin, and eosinophilic cytoplasm. Mitosis is also observed at higher magnification (original magnification 400×; arrow). Immunohistological staining (original magnification, 100×) is positive for synaptophysin (c), chromogranin A (d), and CD56 (e).

Fig. 3

Computed tomography (CT) of the liver obtained 1 and 1.5 years after the initial presentation CT shows small cysts (arrows) in segments 2 (a) and 8 (b) of the liver 1 year after the initial presentation. Six months later, the hepatic cysts (arrows) in segments 2 (c) and 8 (d) of the liver increased in size.

Fig. 4

Ultrasound (US) of the liver obtained at the same time as the computed tomography in Figure 3 US shows a well-margined simple cyst with a thin wall with no solid component.

Fig. 5

Magnetic resonance imaging of the liver obtained after ultrasound (1 year and 9 months after the initial presentation). (a) T2-weighted image shows markedly high signal intensity with a small amount of fluid-fluid level in the cyst (arrow), suggesting intracystic hemorrhage. (b) T1-weighted image shows the cyst as homogenous, with slightly low signal intensity. Diffusion-weighted images show the cyst as having markedly high signal intensity on low b value (c), and low signal intensity on high b value (b = 1000) (d).

Fig. 6

Images of the liver obtained 2.5 years after the initial presentation. (a) Computed tomography (CT) shows a homogenous high attenuation mass in segment 8 of the liver. (b) T1-weighted image shows homogenous high signal intensity. (c) Gadolinium-enhanced fat-suppressed T1-weighted image shows no enhancement, suggestive of hemorrhage. (d) Axial fluorodeoxyglucose positron emission tomography (FDG-PET)/CT shows hypometabolic activity of the lesion. Axial single-photon emission computed tomography (SPECT)/CT image obtained with ¹¹¹In-octreotide (e) and planer image (f) show defects in accumulation consistent with the cystic lesion of the liver.

Fig. 7

Sectioned gross specimen and histopathological findings of surgical specimen of the liver. (a) Gross examination of the tumor demonstrates a remarkably cavitated lesion with hemorrhage. (b) Hematoxylin and eosin staining. Lower magnification (40×) of the sectioned specimen shows a blood-filled cyst with a thin wall consisting of a few layers of the tumor cells (arrows). (c) Higher magnification (100×) of the same tumor shows nesting and cord-like growth pattern similar to that of the lung specimens.