Microlandular adenosis in chronic sinusitis: report of two cases.

Microglandular adenosis (MGA) is a benign mammary lesion defined in 1983 by Clement and Azzopardi , it is characterized by proliferation of small, glands lined by a single type of epithelial cells without myoepithelial component. Recently, Chuang et al (2000) reported a proliferative lesion arising in chronic sinusitis that they thought to be the sinonasal counterpart of the mammary lesion. Here we report two additional cases of this rare lesion. The patients were a 50-year-old male and a 66-year old woman. Both patients received functional endoscopic sinus surgery after suffering of recurrent sinusitis, headache and nasal obstruction. Previous history was negative for exposure to dusts or. CT scan of the sinuses revealed in both patients the presence of a polypoid mucosa without sign of bone destruction. Both patients are disease free 4 years after surgery. Histologically, the haematoxylin and eosin (H & E) sections showed chronic inflammatory reaction with scattered lymphocytes infiltrating a dense hyaline stroma. In addition, in both lesions, a diffuse glandular proliferation was evident. The proliferating glands were present in the subepithelial chorion , close to the mucosal surface, as well as deeply within the fibrovascular stalk of the polyps. In most part of the lesions the glands were small and well formed, showing focally an organoid pattern. Hoowever, in some areas, they were larger and showed a more complex structure with sometimes a cribriform pattern of growth. All the proliferating glands were composed by only one layer of cuboidal cells with bland nuclei. No myoepithelial layer was evident, even using immunohistochemical markers. Anti-laminin and anti-collagen IV antibodies revealed a continuous basal lamina only in some part of the two lesions, while this was completely absent in other parts. The present lesions appear to be morphologically identical to that described by Chuang et al (2000) as microglandular adenosis. However there are some features that make these sinonasal lesions different from the mammary ones.The glands constituting mammary microgladular adenosis lack myoepithelium layer, but show by definition a well formed basal lamina throughout the lesion. In addition , the glands are uniformly small, round and no cribriform pattern is present. The lacking of recurrences in both patients after 3 years, suggests an indolant clincial behaviour. However, we believe that most cases have to be studied to rule out certainly a low grade carcinoma, as was also been suggested by Eusebi (2000) .