A case of lipoma of the parotid gland: Distinguishing the tumor from the fatty parotid gland by the injection of indigo carmine into Stensen's duct for appropriate enucleation.

Lipoma of the parotid gland is a rare tumor. We present a case of such a lipoma in which the parotid parenchyma was stained with indigo carmine, which enabled successful enucleation of the tumor from the fatty parotid gland. A 59-year-old Japanese woman presented with a nontender preauricular lump. Lipoma of the parotid glad was clinically diagnosed according to results of computed tomography and magnetic resonance imaging. The tumor was well demarcated and located just beneath the parotidomasseteric fascia. With the patient under general anesthesia, enucleation of the tumor was attempted; however, the boundary of yellowish tumor was indistinguishable from the fatty parotid gland. Indigo carmine, injected into Stensen's duct, stained the gland but not the tumor. The unstained tumor was then successfully enucleated. Neither postoperative facial nerve dysfunction nor Frey's syndrome was observed during the 2-years follow-up. Histologically, the tumor was composed solely of mature adipocytes within a thin fibrous capsule. The attached parotid gland tissue exhibited fatty replacement. The pathological diagnosis was ordinary lipoma. Many surgeons use superficial lobectomy for parotid lipoma; however, to prevent facial nerve dysfunction and Frey's syndrome, indigo carmine staining is useful for enucleating a lipoma located in the superficial lobe. [ABSTRACT FROM AUTHOR]