Papillary endolymphatic sac tumor: a case report

Abstract

Glandular tumors involving the middle ear are rare and distinguishing between adenoma and adenocarcinoma remains difficult. A distinct subclass of these tumors demonstrates microscopic papillary architecture and has a propensity to erode the petrous bone and extend intracranially. The term "aggressive papillary middle ear tumor" has recently been proposed to describe this more invasive type of middle ear tumor. These tumors cause symptoms even when microscopic in size. Although histologically benign, they have been locally destructive with frequent intracranial extension and patients may die of uncontrolled local disease. These tumors do not metastasize but there is single case report of drop metastasis to the spine in the literature. Hence this tumor must be distinguished from other benign tumors of the middle ear. These rare neoplasms constitute a distinct pathological entity and deserve wider recognition.

Figure 1

Axial MRI T2-weighted image (a) and contrast-enhanced coronal T-weighted image (b) showing heterogenous intensely enhancing mass involving left petrous temporal bone causing destruction of bone, extending medially left cerebellopontine angle cistern and inferiorly below base of skull. Axial CT scan (c) showing destruction of extensive destruction of the posterior petrous bone and middle ear structures.

Figure 2

Microscopy shows typical papillary structures (2(a), H&E × 100), lined by benign looking low cuboidal epithelial cells (2(b), H&E × 200). Tumor cells are immunopositive for cytokeratin (2(c), IHC (CK)[Daco] × 200) and S100 (2(d), IHC (S100)[Daco] × 200).