Low grade glandular lesions of the sinonasal tract: a focused review

Abstract

The sinonasal tract is a complex anatomic site with an exhaustive list of possible diagnoses. While most biopsies or resections encountered routinely consist of common diagnoses such as inflammatory polyps and papillomas, occasional cases are more difficult, and separating reactive or benign from malignancy can be challenging. One of the most poorly understood and daunting categories is low grade glandular or tubular proliferations, particularly on small biopsies. Possible diagnoses such as reactive lesions, respiratory epithelial adenomatoid hamartoma (REAH), seromucinous (glandular) hamartoma (SH) and low grade sinonasal adenocarcinomas (LGSNAC) must be entertained. REAH is composed of respiratory epithelial lined submucosal glands with variable connection to the surface and periglandular hyalinization. SH is a tubular proliferation reminiscent of normal serous glands which may be associated with REAH. LGSNAC is a diverse group of bland tubular and/or papillary tumors, which have a recurrence potential but an as yet uncertain potential for metastasis or mortality. The management for these lesions can be vastly different and conservative management is preferable, making this distinction more than academic. However, complicating this category are controversies surrounding their nature as reactive lesions versus neoplasms, the histologic and immunohistochemical overlap, and possible precursor relationships between some of them.

Fig. 1

a A typical example of a REAH showing back-to-back ciliated respiratory type glands with connection to the surface and periglandular hyalinization. b Some cases show occasional areas of so-called atrophy with attenuation of the epithelial lining and a pseudovascular appearance. Note the typical periglandular hyalinization

Fig. 2

Some cases show focal or occasionally prominent mucinous change. The overall architecture in these areas is the same as a typical REAH but the lining is entirely mucinous. This case had typical REAH in other foci

Fig. 3

a Seromucinous hamartomas show a lobular growth of small serous glands. Note the REAH-like element at the top left of the field; a feature seen in most seromucinous hamartomas. b Seromucinous hamartomas typically show “budding” of the serous glands from the respiratory elements. Note the edematous nature of the background stroma. c High power view of the bland small serous glands. Note the lack of cribriforming. This case showed periglandular hyalinization around the serous elements

Fig. 4

High power of a hybrid lesion with seromucinous hamartoma and REAH elements in equal proportions

Fig. 5

a An occasional low-grade ITAC may show minimal atypia or complexity of architecture and may be mistaken for a seromucinous hamartoma. The cells are slightly more columnar however and the glands do show a back-to-back growth pattern with loss of the lobular arrangement. b The same case as in Fig. 5a shows nuclear positivity for CDX2. This case was also positive for CK20 (not shown)

Fig. 6

a Low-grade non-intestinal sinonasal adenocarcinomas (LGSNAC) show bland serous glands but usually show some degree of architectural complexity. Note the more haphazard growth than in seromucinous hamartoma, the micropapillary tufts and the focal cribriforming. These features are not seen in seromucinous hamartoma. This case showed tubulocystic features. b Some cases of LGSNAC show more solid growth with focal tubular formations. Note the low grade features of the nuclei. c Occasional cases are more exophytic and have a more prominent papillary architecture. This case also highlights occasional apical snout formation and calcification