[Malignant transformation of a tubular adenoma in the paranasal sinuses?].

Background: Whereas a tubular adenoma is a unique finding within the paranasal sinuses, intestinal adenocarcinomas are especially in patients with long-term exposure to wood dust, common tumours in this location.

Case: In a 65 year old joiner endonasal sinus surgery performed to treat suspected chronic pansinusitis brought up by chance the histological finding of a tubular adenoma. As the patient at first refused surgical revision, but magnetic resonance imaging during follow-up revealed evidence for a space occupying lesion affecting the ethmoid and sphenoid sinuses revision surgery took place one year later. Histopathological evaluation now found a papillary adenocarcinoma. Clinical follow-up and magnetic resonance imaging one year after second surgery found no evidence for tumour recurrence.

Conclusions: Progression of a tubular adenoma to an adenocarcinoma like in the adenoma-carcinoma model well known for colorectal carcinomas has so far not been observed within the paranasal sinuses. But, an adenocarcinoma already present at the time of first surgery can not be ruled out completely in the presented case as histopathological evaluation may have failed to detect an adenocarcinoma in the available specimens after first surgery. Either malignant transformation of a tubular adenoma had occurred or proof of an adenocarcinoma has failed with misdiagnosis of a tubular adenoma. A tubular adenoma as well as an adenocarcinoma require complete resection and careful clinical and radiological follow-up to avoid adenocarcinoma development from a tubular adenoma or to detect an adenocarcinoma by histological evaluation of the whole specimen.