Clear Cell “Sugar” Tumor (PEComa)
Key Facts
Terminology
Benign intrapulmonary neoplasm with prominent clear cells
Etiology/Pathogenesis
Myo-melanocytic differentiation (PEComa)
Clinical Issues
Although tumor is more common in adults, it has been reported in children
No gender predilection
Asymptomatic
Macroscopic Features
Peripheral tumor
1-7 cm in diameter
Microscopic Pathology
Sheets of clear cells with dilated vascular spaces
Ancillary Tests
Periodic acid-Schiff
Positive
Top Differential Diagnoses
Clear cell carcinoma, primary or metastatic
Sugar tumor is negative for epithelial markers
Sugar tumor lacks nuclear atypia &/or mitotic activity
Diagnostic Checklist
Clear cells with abundant dilated vascular vessels mimicking hemangiopericytoma
 Gross photograph shows a well-circumscribed intrapulmonary clear cell “sugar” tumor  . The cut surface is homogeneous and light tan. |
 Sugar tumor is seen with prominent clear cell proliferation. Note the absence of cellular atypia, necrosis, and mitotic activity. |
TERMINOLOGY
Synonyms
Clear cell tumor
Definitions
Benign intrapulmonary neoplasm with prominent clear cells
ETIOLOGY/PATHOGENESIS
Etiology
Recently sugar tumor has been regarded as part of the family of tumors designated as PEComas
Myo-melanocytic differentiation
CLINICAL ISSUES
Epidemiology
Age
Although tumor is more common in adults, it has been reported in children
Gender
No gender predilection
Presentation
Asymptomatic
Fever
Anemia
Pneumonia
Elevated platelet count
Elevated erythrocyte sedimentation rate
Hemoptysis (rarely)
History of tuberous sclerosis
Treatment
Surgical approaches
Complete surgical resection
Prognosis
Excellent
MACROSCOPIC FEATURES
General Features
Peripheral tumor
Well circumscribed but not encapsulated
Tan to pink in color
1-7 cm in diameter
MICROSCOPIC PATHOLOGY
Histologic Features
Sheets of clear cells with dilated vascular spaces
Absence of nuclear atypia
Absence of necrosis &/or hemorrhage
Absence of mitotic activity
Occasionally cells may adopt a spindle cell appearance
Predominant Pattern/Injury Type
Sheets
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