Clear cell 'sugar' tumor of the lung: Association with lymphangioleiomyomatosis and multifocal micronodular pneumocyte hyperplasia in a patient with tuberous sclerosis

We report the unique association of a clear cell 'sugar' tumor of the lung (CCTL) in a 32-year-old woman with tuberous sclerosis (TSC), lymphangioleiomyomatosis (LAM), and multifocal micronodular pneumocyte hyperplasia (MMPH). Chest radiographs demonstrated a peripheral solitary 1.0- cm lingular nodule, diffuse emphysematous changes, and bilateral pneumothorax. Microscopic examination of the coin lesion showed an unencapsulated tumor composed of round to oval to locally spindled cells with distinct cellular borders, abundant clear to eosinophilic granular cytoplasm, prominent thin-walled blood channels, and focal hyaline stroma. Rare multinucleated cells were identified, and neither necrosis nor mitotic figures were seen. Tumor cells contained abundant diastase-sensitive intracytoplasmic glycogen, as demonstrated with periodic acid-Schiff stains. Tumor cell immunoreactivity for HMB-45 and nonreactivity for cytokeratin supported the diagnosis. The lung tissue also contained MMPH and smooth muscle proliferations diagnostic of LAM. The histogenesis of CCTL remains controversial, and similarities between this lesion and both LAM and angiomyolipoma (AML) raise the possibility that these lesions are related not only to each other, but that CCTL should be added to the spectrum of pulmonary manifestations of TSC.