Discussion
Endometroid adenocarcinoma (type I) is the
most common histologic subtype accounting 80-85%
of all EC. While clear cell carcinoma (type II)
accounting for only 1-5%. Type II EC occurs in older
population and associated with aggressive clinical
behaviour and had poor prognosis compared to type I
EC. MEC is a rare histological variant composed of
type I and type II EC. It is not considered as a
morphological variant of endometrioid cancer that
stimulate type II component. WHO mandates IHC
staining to confirm subtype of type II and any amount
of type II component in endometrioid carcinoma
qualified as MEC. It has aggressive behaviour and
poor outcome compared to endometroid carcinoma
(type I) and similar to pure serous or clear cell
carcinoma of endometrium (Type II). Kaban et al in
2018 also proposed similar result that, MEC have
same prognosis and risk of metastases as patients with
pure endometrial serous carcinoma.4
Diagnosis of MEC is diagnosis of exclusion.
A pathologic morphology on H & E stain is
insufficient to diagnose and it mandates the
conformation of the mixed nature by IHC. A
Combination of ER, PR, p53 and napsin are used to
distinguish type I from type II EC. A positivity of ER,
PR and a negativity of napsin favours endometroid
subtype whereas napsin positivity favours the
diagnosis of clear cell subtype. In endometroid
subtype p53 is almost always negative, where as it may rarely be positive in clear cell subtypes as
opposite to its high positivity in serous histologies. MEC is consider as high grade regardless of
the amount of type II component in it.5 Wenhui et al in
2019 reported that any amount of non-endometroid
component in MEC indicate poor prognosis and
warrant rigorous adjuvant treatment and close follow
up. They also reported better survival in MEC with
aggressive treatment compared to pure non
endometroid carcinoma.6
Treatment plan should be made, considering
the aggressive counterpart in MEC as planned in our
case. Comprehensive surgical staging is cornerstone
of management in type II EC. These patients often
experience local, nodal and distant recurrence.
According to Postoperative Radiation Therapy in
Endometrial carcinoma (PORTEC-3) trial high risk
endometroid and early-stage clear cell carcinoma
should be treated with chemo-radiation. Similarly in
our case patient also received comprehensive surgical
s t a g i n g f o l l o w e d b y E B RT a n d a d j u v a n t
chemotherapy considering aggressive nature of clear
cell carcinoma of EC even in stage IB for better
survival.
Conclusion
As MEC has inferior survival outcome and
high chance of metastasis compared to endometroid
adeno carcinoma they need rigorous adjuvant
treatment and follow up.
References
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