3.b.iii.1 Invasive Mucinous Adenocarcinoma Endocervical-type

Invasive Mucinous Adenocarcinoma Endocervical type

Invasive Mucinous Adenocarcinoma Endocervical type

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Invasive mucinous endocervical adenocarcinoma is less common than invasive squamous cell carcinoma, but its prevalence has been increasing in the last decades. The conventional type of endocervical adenocarcinoma is of mucinous type but there are other less frequent subtypes, such as intestinal, endometrioid, serous and clear cell types. The diagnosis of invasive endocervical adenocarcinoma is based on the presence of infiltrative malignant glands. Invasive glands often show morphological features similar to adenocarcinoma situ, which include nuclear stratification, increased nuclear size, hyperchromasia, mitotic activity and apoptosis. Therefore, establishing the difference between invasive and in situ adenocarcinoma relies mainly on the presence of architectural disturbances. The diagnosis of invasion can be easily established whenever malignant glands are seen deep into the cervical stroma, or if there is confluent growth pattern, incomplete gland formation or individual cells. However, in many cases with minimal stromal invasion, the distinction between in situ and invasive disease can be very challenging. The invasive component will show a loss of the normal lobular architecture as well as cribriform growth. Depth of invasion and tumor diameter are important prognostic factors for endocervical adenocarcinoma. Measurement of these parameters is particularly difficult in cases where both in situ and invasive disease are admixed. For more information on how to measure depth of invasion and tumor diameter, see our tutorial on morphometry (coming soon).

The differential diagnosis of endocervical adenocarcinoma includes microglandular hyperplasia of the cervix, which can usually be easily diagnosed by the presence of subnuclear vacuoles, absence of significant atypia or mitotic activity.

Distinction between and endocervical adenocarcinoma and endometrial endometrioid adenocarcinoma on a curetting specimen may be difficult. Elongated nuclei would be more in favor of an endocervical origin and rounded nuclei of an endometrial origin. Immunohistochemistry may be helpful: endocervical adenocarcinomas are usually p16+, CEA+, vimentin-, ER- and endometrial adenocarcinomas are p16-, CEA-, vimentin+ and ER+. However, it is to note that poorly differentiated endometrial adenocarcinoma can express p16 (Ref 1).

Reference:
Faragalla H, Khalifa MA, Ismiil N, Nofech-Mozes S, Dubé V, Ghorab Z, Saad RS. Does p16 Expression In Undifferentiated Carcinoma Of The Uterus Exclude Its Endometrial Origin? Modern Pathology 2010 Jan; 23 (Suppl 1).