대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Clear cell tumor of the lung (sugar tumor, perivascular epithelioid cell tumor)

Radiologic Findings

Chest radiograph shows a solitary pulmonary nodule in the left lower lung. Chest CT reveals a 1cm, well-defined, round nodule in the left lower lobe (LLL). Follow-up chest CT scan which was taken after 3 months shows no interval change of this well enhancing nodule. This lesion has maximal SUV of 1.0 on PET CT scan.
VATS wide wedge resection of the LLL was performed. Pathology showed large polygonal cells with abundant clear and eosinophilic cytoplasm. This morphology and strong reactivity with human melanoma black-45 (delineating perivascular epithelioid cell differentiation) supported the diagnosis of clear cell tumor of the lung. Vimentin was positive but cytokeratin, CD 10 and renal cell carcinoma marker were negative.

Brief Review

Clear cell tumor of the lung (CCTL) is a rare mesenchymal neoplasm characterized by abundant cytoplasmic Periodic acid-Schiff positive glycogen. It is also known as sugar tumor or perivascular epithelioid cell (PEC) tumor.
CCTL is an extremely rare tumor, first described by Liebow and Castleman in 1963. Most CCTLs are benign (only five malignant cases have been reported so far in English literature).
CCTLs manifest as an incidental solitary pulmonary nodule in asymptomatic patients (except for few cases with nonspecific symptoms of hemoptysis, fever or reactive thrombocytosis). Patients with CCTLs usually range in age from 40 to 60 years and are equal in prevalence among both genders.
Radiologically, the tumor appears as a peripheral, well-defined, enhancing, and round nodule (1~4 cm in diameter) without cavitation or calcification. Histologically, the tumor comprises round or oval cells with distinct cell borders and abundant eosinophilic cytoplasm (containing numerous glycogen granules, hence the name sugar tumor). The cells usually have prominent nucleoli, but mitotic figures and foci of necrosis are absent, suggesting the benign nature of the tumor. The tumor is highly vascular, with numerous thin-walled sinusoidal vessels.
Treatment usually is surgery by either wedge resection or lobectomy with no adjuvant therapy.

References

1. S Das, SV Cherian, N Das, WA Hamarneh, AS Garcha et al. A 52-year-old smoker with an incidental pulmonary nodule. Chest 2012;141(5):1346-1350
2. H Lim, HY Lee, J Han, YS Choi, KS Lee. Uncommon of the uncommon: malignant perivascular epithelioid cell tumor of the lung. KJR 2013;14(4):692-696

Keywords

Lung, Benign tumor,