Mesonephric Adenocarcinoma of the Uterine Corpus: A Report on 2 Cases With Comparison to Its Cervical Counterpart

Mesonephric Adenocarcinoma of the Vagina Harboring TP53 Mutation

Mesonephric adenocarcinoma (MA) of the female genital tract is a rare but distinct entity, exhibiting unique morphological, immunophenotypical, and molecular characteristics. Vaginal MA is hypothesized to arise from the mesonephric remnants located in the lateral vaginal wall. A 52-year-old woman presented with vaginal bleeding. Physical examination revealed a protruding mass in the left vaginal wall. Pelvic magnetic resonance imaging revealed a 2.5-cm mass arising from the left upper vagina and extending posterolaterally to the extravaginal tissue. The punch biopsy was diagnosed as poorly differentiated adenocarcinoma. She received radical surgical resection. Histologically, the tumor displayed various architectural patterns, including compactly aggregated small tubules, solid cellular sheets, endometrioid-like glands and ducts, intraluminal micropapillae, cribriform structure, and small angulated glands accompanied by prominent desmoplastic stroma. The tubules and ducts possessed hyaline-like, densely eosinophilic intraluminal secretions. The tumor extended to the subvaginal soft tissue and had substantial perineural invasion. Immunostaining revealed positivity for the mesonephric markers, including GATA3, TTF1, and PAX2, while showing very focal and weak positivity for estrogen receptor and negativity for progesterone receptor. Additionally, we observed a complete absence of p53 immunoreactivity. Targeted sequencing analysis revealed that the tumor harbored both activating KRAS p.G12D mutation and truncating TP53 p.E286* mutation. A thorough review of the previous literature revealed that 4.5% (3/67) of vaginal/cervical MAs and 0.9% (1/112) of uterine/ovarian mesonephric-like adenocarcinomas harbor TP53 mutations, indicating that this is very uncommon in malignant mesonephric lesions. In summary, we presented a rare case of vaginal MA uniquely harboring pathogenic TP53 mutation, resulting in p53 aberration.

Atypical Mesonephric Hyperplasia of the Uterus Harbors Pathogenic Mutation of Kirsten Rat Sarcoma 2 Viral Oncogene Homolog (KRAS) and Gain of Chromosome 1q

BACKGROUND/AIM

Mesonephric carcinoma (MNC) is a rare but notable entity of the female genital tract. While many researchers have acknowledged and studied MNC, much remains unknown on the characteristics of mesonephric remnant (MNR) or hyperplasia (MNH). There has not been any study examining the molecular features of MNR and MNH so far. The aim of this study was to investigate the clinicopathological and molecular characteristics of ten uterine mesonephric lesions, including two MNRs without atypia, four MNHs without atypia, and three MNHs with atypia.

MATERIALS AND METHODS

We reviewed the electronic medical records and all available slides of ten cases from multiple institutions. Targeted sequencing and array comparative genomic hybridization were performed.

RESULTS

Three atypical MNHs displayed nuclear enlargement, mild-to-moderate nuclear pleomorphism, and nuclear membrane irregularity, and harbored pathogenic Kirsten rat sarcoma 2 viral oncogene homolograt sarcoma 2 viral oncogene homolog (KRAS) mutation. Two of those that co-existed with MNC harbored the same sequence alterations as each of their adjacent MNC. One of the three atypical MNHs harbored chromosome 1q gain.

CONCLUSION

Atypical MNH is a potential premalignant lesion in which KRAS mutation and chromosome 1q gain play an important role in the early stage of mesonephric carcinogenesis.