993 – Late metastasis of papillary serous cystoadenocarcinoma to an axillary lymph node simulating occult breast carcinoma: a case report

Abstract

Introduction: Papillary serous cystadenocarcinoma is the most common epithelial tumor of the ovary; it has an aggressive course, a high recurrence rate, and is often diagnosed at advanced stages. The incidence of metastasis from ovarian cancer to the breast and/or axillary lymph nodes ranges from 0.03% to 0.6%. In cases of isolated axillary lymph node
metastasis without breast involvement, the frequency is lower, described almost exclusively in case reports and small
case series. It represents a diagnostic challenge, as axillary lymphadenopathy is frequently associated with breast cancer.
Case report: A 71-year-old woman was treated for bilateral papillary serous cystadenocarcinoma of the ovaries in 2004.
She sought medical care in 2025 with no breast complaints, but with a palpable, hardened lymph node in the left axilla
measuring 1.5 cm. Ultrasound revealed an atypical lymph node. Mammography and magnetic resonance imaging showed
no suspicious breast lesions, but lymphadenopathy with diffuse cortical thickening. Core biopsy and immunohistochemistry revealed papillary carcinoma, estrogen receptor (ER)-positive and progesterone receptor (PR)-negative, suggesting
a primary site in the female genital tract. After negative metastatic staging, she underwent left axillary lymphadenectomy. Histopathology and immunohistochemistry demonstrated three lymph nodes with papillary metastatic neoplasia,
human epidermal growth factor receptor 2 (HER2)-negative, diffuse ER-positive, and paired box gene 8 (PAX-8)-positive,
with focal PR and p53 positivity, favoring Müllerian epithelium as the primary site. Markers specific to the breast, lung,
and thyroid were negative. She is currently under oncological follow-up.
Discussion: Late metastasis of ovarian cystadenocarcinoma to the axillary lymph node, mimicking occult breast carcinoma, represents an exceptional manifestation of tumor recurrence, especially when it occurs after a long disease-free
interval. The identification of this rarity expands knowledge regarding late dissemination and reinforces the need to consider a Müllerian origin in the differential diagnosis of axillary lymphadenopathy in women with a distant history of gynecological neoplasia and no breast lesions.
Ethics: Research Ethics Committee Approval (CAAE 85735824600005553).