2 - AXILLARY SCHWANNOMA MIMETIZING LOCALLY ADVANCED BREAST CANCER: A CASE REPORT

Abstract

Schwannomas are benign, rare tumors that arise from the myelin sheath or peripheral nerves. Usually, they occur in the adult
age, being uncommon in children. They may distort the nervous path and, when adjacent to bones, can lead to fractures.
The incidence of this kind of tumor in the axilla is approximately 5%, and in the breasts, it is 2.6%. Fragment biopsies can
elucidate the diagnosis, but the patient might present intense pain during the procedure. Macroscopically, Schwannomas
have a fibroelastic consistency and a fibrous capsule. Microscopically, the spindled Schwann cells are seen, and hypercellular areas (Antoni A) are alternated with hypocellular areas (Antoni B), all of which show a positive reaction to the S100
protein during immunohistochemical staining. Small and asymptomatic Schwannomas do not require any kind of treatment, and a follow-up of every 6 months with ultrasound examinations is a viable option. For symptomatic cases, the
treatment is lumpectomy, with extra care to preserve the adjacent nerve whenever that is possible. This surgery allows satisfactory results, with low rates of malignization and relapse. This article aims to report the case of a 37-year-old woman
who presented with a palpable lump in the right axilla, diagnosed as a Schwannoma. Its importance comes from the rarity of the tumor and its resemblance to locally advanced breast cancer. MML, female, 37 years old, Caucasian, single, was
referred to the mastology service of a Medical Practice localized in the south of São Paulo, after presenting with a palpable, nonpainful lump in the right axilla, with progressive and accelerated growth. An ultrasound examination showed
a solid-cystic, hypoechogenic nodule, with regular margins, that measured up to 6.4 cm. After core biopsy, the histology
of the lump was described as a proliferation of spindle-like cells, and the immunohistochemical staining showed a positive reaction to the S100 protein, which confirmed the diagnosis of Schwannoma. The patient underwent a lumpectomy
and presented with hypoesthesia and loss of strength in the upper right limb, which had spontaneous resolution after 2
weeks of follow-up.