28612 – LEFT AXILLARY SCHWANNOMA WITH MALIGNANT-LIKE LYMPH NODE INVOLVEMENT: A RARE CASE REPORT

Abstract

Introduction: The schwannoma was first described in 1908 by Verocay, characterized as a neoplasm arising from the
nerve sheath on the periphery of Schwann cells. Collins, in 1972, reported the first case of schwannoma located in the breast. Tumors of non-epithelial origin of the breast are extremely rare, accounting for 2%–3% of all schwannomas, and only
0.2% of all breast tumors are schwannomas. Axillary location accounts for 5% of all schwannomas, and malignancy is even
rarer, representing 5%–10% of all sarcomas, primarily malignant in males. These tumors are usually located in the head,
neck, arms, legs, torso, and chest, with axillary involvement being uncommon. The etiology of schwannomas is uncertain;
however, they are believed to be related to metastatic diseases, radiotherapy, and advanced age. Our report describes a
43-year-old female patient with an axillary schwannoma exhibiting malignant-like lymph node involvement, with no risk
factors for neoplasm development, making this case extraordinary. Schwannomas can occur at any age, but the highest
incidence is in individuals aged 40 years or older, with no predilection for sex or ethnicity. Symptoms are often absent or
present as a mass associated with paresthesia and/or radiating pain, which complicates early diagnosis. Diagnosis is usually delayed because the signs and symptoms can be confused with various benign and malignant lesions, such as fibroadenomas, phyllodes tumors, mesenchymal neoplasms, or breast cancer. Although rare and difficult to diagnose, the potential for malignancy and metastasis highlights the importance of studying this pathology, underscoring the need for early
diagnosis, prompt, aggressive therapy. The literature reports approximately 37 cases of mammary and axillary neurilemomas, mostly of benign course, with only four reports of malignant schwannomas of the breast. To our knowledge, this is
the only report of an axillary schwannoma with malignant lymph node involvement demonstrating satisfactory clinical
and laboratory evolution. Methodology: Study Modality: This is a descriptive observational study of a case report type.
Study Location: This research was conducted at a tertiary hospital in the state of Santa Catarina. Study Population and
Sample: The sample of the present study consisted of a single clinical case involving one individual, female by biological sex.
Ethical Procedures: The study complies with the ethical principles outlined in Resolution No. 466, enacted on December
12, 2012, by the National Health Council, which addresses testing and research involving human subjects and the rights
guaranteed to them. The participant was informed about the study’s objectives, methods, potential benefits, and any discomforts or constraints it might entail. The participant received a form of informed consent, which she signed, thereby
authorizing her participation in the study. It was also emphasized that participation in this study was voluntary; therefore, if the patient did not wish to participate, she had the right to refuse at any point during the research. Conclusion: It
is possible to state that axillary schwannomas are rare, but should be considered in the differential diagnosis of axillary
nodules. In the literature, there are only four reports of malignant schwannomas in the breast. Therefore, the case described below is unique and involves a patient with an expanding left axillary nodule, with no prior history of disease or
previous surgical or radiotherapeutic procedures, making the case unusual. The diagnosis was only confirmed through
immunohistochemical analysis after tumor excision, which established the diagnosis of malignant axillary schwannoma
with lymph node involvement requiring adjuvant chemotherapy and radiotherapy. Thus, this emphasizes the importance
of an early diagnostic method and effective treatment approach, given the difficulty in diagnosis and the rarity of the case.