Invasive Stratified Mucin-producing Carcinoma (ISMC) of the Uterine Cervix: Clinicopathological and Molecular Characteristics With Special Emphasis on the First Description of Consistent Programmed Death-ligand 1 (PD-L1) Over-expression

Invasive stratified mucin-producing carcinoma (ISMC) of the cervix: a clinicopathological and molecular analysis of 59 cases with special emphasis on histogenesis and potential therapeutic targets

AIMS

This study aimed to better characterize the clinical and molecular features in invasive stratified mucin-producing carcinoma (ISMC), an uncommon aggressive subtype of endocervical adenocarcinoma (EAC).

METHODS AND RESULTS

We recruited 59 ISMC for clinicopathological analysis, immunohistochemistry (n = 56), and targeted next-generation sequencing (n = 17). Our cases contained 29 pure and 30 mixed-type ISMC. Five patients developed local recurrence at 6-32 months (median: 13 months), and died of disease at 16-55 months (median: 16 months). Pure and mixed-type ISMC showed no significant difference in overall survival and tumour relapse (P > 0.05) except larger tumour size in the pure-type (P = 0.009). Compared to the usual-type EAC (n = 217), ISMsC were more frequently associated with large tumour size (P = 0.003), advanced FIGO stage (P = 0.017), lymph node metastasis (P = 0.022), Silva pattern C (P < 0.001), and poor overall survival and short tumour recurrence. SOX2 expression was observed in 82.1% (46/56) ISMC, substantially higher than p63 expression (P < 0.001), while positive SOX17 was present in 3.6% (2/56) cases. PD-L1 was positive in 41/56 ISMC (73.21%) (combined positive score: range: 1-92, median: 22). Three ISMC patients (17.65%) had PIK3CA mutations, while one each (5.88%) patient harboured an ERBB2, TP53, STK11, and PTEN mutation, respectively.

CONCLUSION

We conclude that ISMC is clinically more aggressive than the usual-type EAC. ISMC may originate from cervical reserve cells with bidirectional differentiation. PD-L1 overexpression and the molecular profiles raise the possibility that a subset of ISMC patients may benefit from anti-PD-L1 immunotherapy and other targeted therapy, such as mTOR inhibitor and T-DM1.

Endocervical Adenocarcinoma Showing Microcystic, Elongated, and Fragmented (MELF) Pattern of Stromal Invasion: A Single-Institutional Analysis of 10 Cases with Comprehensive Clinicopathological Analyses and Ki-67 Immunostaining

Microcystic, elongated, and fragmented (MELF) pattern of invasion has seldom been documented in endocervical adenocarcinoma (EAC). The aim of this study was to analyze the clinicopathological characteristics of EAC showing MELF pattern. We collected the clinicopathological information of 10 cases of EAC with the MELF pattern and conducted polymer-based immunostaining for Ki-67 (dilution 1:200, clone MIB-1) on these cases. Ki-67 expression was assessed using the average estimation within the hotspot method. All tumors were human papillomavirus-associated EAC with Silva pattern C. All except one tumor exceeded 3 cm in size. Five tumors involved the entire thickness of the cervical stroma, and four tumors extended into the parametrium. Lymphovascular space invasion was identified in six cases. Two patients developed metastatic recurrences in the para-aortic lymph nodes and lungs, respectively. The MELF area showed significantly lower Ki-67 labelling index than that of a conventional tumor area. We confirmed our previous observation that the MELF area displayed lower proliferative activity than the conventional tumor area of EAC. We also demonstrated that patients with EAC showing MELF pattern had several adverse clinicopathological characteristics reflecting aggressive behavior. On the other hand, since the frequencies of post-operative recurrence and disease-related mortality that occurred during the follow-up period were relatively low, further investigations are warranted to clarify the prognostic value of MELF pattern in EAC patients.