nodular adenosis

Nodular adenosis is a mammary adenosis presenting, as a mass (as nodular adenosis or adenosis tumor ) or as calcifications on imaging.

Sclerosing adenosis is a form of adenosis in which there is an expansion of terminal duct lobular units (TDLU) due to proliferation of glandular components, accompanied by stromal proliferation which is usually dense and hyalinized with resultant compression and distortion of glands.

Though it is often found as a microscopic lesion accompanying fibrocystic diseases, it rarely presents as a palpable mass when it is also called adenosis tumor or better designated as nodular sclerosing adenosis mimicking carcinoma clinically and mammography.

Since the mammographic appearance is often indistinguishable from malignancy, fine needle aspiration cytology (FNAC), with or without a core biopsy is mandatory to rule out breast cancer.

Nodular sclerosing adenosis or adenosis tumor is an unusual presentation of sclerosing adenosis as a palpable mass, and may clinically, radiologically and pathologically simulate breast malignancy.

It usually presents in the perimenopausal age group. It poses a diagnostic confusion with infiltrating lobular carcinomas and tubular carcinomas even in histological sections, but is identified by the relative preservation of overall lobular architecture, the compressed glands, lack of atypia, the retention of two cell layers, and the confirmation of the presence of myoepithelial cells by immunohistochemistry.

It could be associated with mammary microcysts , apocrine metaplasia , luminal histiocytes and pseudopapillomas , called glomeruloid structures.

The presence of microcalcifications in mammography, the pseudoinvasive growth pattern resulting from compression of glands, rare but actual invasion of nerves and apocrine metaplasia add to the diagnostic confusion in many cases. Howev

er, in tissue sections, especially core biopsies, the identification of myoepithelial cells and basement membrane by immunohistochemistry is really useful in difficult cases.

Although core needle biopsy provides a definite diagnosis in most cases, a coexisting cancer may be missed due to sampling error.

There is a case report of sclerosing adenosis occurring within the lymph node, also mimicking metastatic cancer.

It is important to distinguish sclerosing adenosis from other benign lesions due to the fact that it is associated with small but definite risk of invasive carcinoma and the risk increases if it is associated with atypical hyperplasia.

Sclerosing adenosis may also be associated with collagenous spherulosis.

Open references

 Nodular sclerosing adenosis of breast: A diagnostic pitfall in fine needle aspiration cytology. 2015. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3643363/ (Free)