Case Presentation: Herein we present the case of a 47-years-old woman with an history of luminal-B/Her-2 negative invasive NST carcinoma in her right breast treated with primary chemotherapy and mastectomy in 2019. In February 2024, a hard lump (~18 cm) of the right chest wall and close to the breast implant was identified. Histologically the tumor revealed cystic spaces with papillary projection, lined by tall columnar cells with basally located bland nuclei and apical mucin, and filled with extracellular mucin. Cytological atypia was mild to moderate; mitotic figures were rare. On immunohistochemistry, positivity for Mammaglobin and GCDFP15 and negativity for CK20, CDX2, TTF1, Napsin, S100 protein and PAX8 confirmed the mammary origin, excluding gastrointestinal, pulmonary and ovarian counterparts. Tumor displayed a triple-negative immunophenotype. Diagnosis: Primary mucinous cystoadenocarcinoma (MCA) of the breast. Methods and Results: Next Generation Sequencing with a multigene panel targeting 1385 genes and 21043 exonic regions, including 507 genes involved in cancer gene fusions (TruSight RNA Pan-Cancer Panel, Illumina) was performed. A 67% of missense variants, 3% of frameshift elongation and 4% stop gained were mainly annotated, specifically on AKT1, EGFR, FANCA, BCL-10, CTCF, RUNX1 genes likely pathogenic with an allele frequency ≤5%. Conclusions: Breast MCA is an extremely rare tumor and has been recognized as a distinct entity in the recent 5th edition of WHO classification of tumors of the breast, 2019. To date, only 37 cases have been reported in the literature, including our case; therefore its molecular pathways, prognosis and therapeutic schemes are barely known. To our best knowledge, the case here reported is the first in the literature to display mutations in AKT1, EGFR, FANCA, BCL-10, CTCF, RUNX1 genes, that might contribute to a worse prognosis on one hand but may represent potential targets for novel therapeutic approaches on the other.
MOLECULAR ANALYSIS OF PRIMARY MUCINOUS CYSTOADENOCARCINOMA OF THE BREAST: A CASE REPORT (Section: Breast Pathology)
Roberta Iozzo;Eugenia Belcastro;Antonio Giuseppe Naccarato;Cristian Scatena
2024-01-01
Abstract
Case Presentation: Herein we present the case of a 47-years-old woman with an history of luminal-B/Her-2 negative invasive NST carcinoma in her right breast treated with primary chemotherapy and mastectomy in 2019. In February 2024, a hard lump (~18 cm) of the right chest wall and close to the breast implant was identified. Histologically the tumor revealed cystic spaces with papillary projection, lined by tall columnar cells with basally located bland nuclei and apical mucin, and filled with extracellular mucin. Cytological atypia was mild to moderate; mitotic figures were rare. On immunohistochemistry, positivity for Mammaglobin and GCDFP15 and negativity for CK20, CDX2, TTF1, Napsin, S100 protein and PAX8 confirmed the mammary origin, excluding gastrointestinal, pulmonary and ovarian counterparts. Tumor displayed a triple-negative immunophenotype. Diagnosis: Primary mucinous cystoadenocarcinoma (MCA) of the breast. Methods and Results: Next Generation Sequencing with a multigene panel targeting 1385 genes and 21043 exonic regions, including 507 genes involved in cancer gene fusions (TruSight RNA Pan-Cancer Panel, Illumina) was performed. A 67% of missense variants, 3% of frameshift elongation and 4% stop gained were mainly annotated, specifically on AKT1, EGFR, FANCA, BCL-10, CTCF, RUNX1 genes likely pathogenic with an allele frequency ≤5%. Conclusions: Breast MCA is an extremely rare tumor and has been recognized as a distinct entity in the recent 5th edition of WHO classification of tumors of the breast, 2019. To date, only 37 cases have been reported in the literature, including our case; therefore its molecular pathways, prognosis and therapeutic schemes are barely known. To our best knowledge, the case here reported is the first in the literature to display mutations in AKT1, EGFR, FANCA, BCL-10, CTCF, RUNX1 genes, that might contribute to a worse prognosis on one hand but may represent potential targets for novel therapeutic approaches on the other.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
