Primary melanoma of mammary skin

A 58-year-old woman with a history of diabetes presented with a bleeding, heterochromatic, and irregular lesion that demonstrated progressive growth in the left breast. Physical examination revealed a hyperpigmented, exophytic, and friable area in the tail of the breast, along with a palpable, mobile 1 cm adenopathy in the left axilla (Fig. 1A, B). Punch biopsy confirmed invasive melanoma. Ultrasound of the left breast showed skin thickening measuring 4.5 mm. Chest CT scan identified skin thickening in the tail of the left breast up to 4.6 mm and a hypodense ovoid lesion measuring 4 × 5 mm. Multiple left axillary lymph nodes measuring 17 × 10 mm were also present (Fig. 1C, D). No additional lesions were detected elsewhere in the body.

Figure 1.

Physical examination findings. (A, B) Hyperpigmented, irregular lesion on the tail of the left breast, measuring 4 cm. (C) Coronal chest tomography with contrast; arrow indicates skin thickening in the tail of the left breast and an ovoid image measuring 4 x 5 mm. (D) Left axillary lymph nodes measuring 17 x 10 mm (arrow).

A quadrantectomy of the left breast with sentinel lymph node biopsy was performed, which revealed micrometastasis. Subsequent axillary dissection and reconstruction were conducted using Holmström's thoracodorsal flap (Fig. 2). Pathological examination identified an invasive, ulcerated melanoma measuring 6.3 cm, with surgical margins of 1.3 cm. The Breslow thickness was 7 mm, and the Clark level was IV, indicating invasion into the reticular dermis. Immunohistochemical analysis showed positivity for S-100, Melan-A, and HMB-45, with a Ki-67 index of 5% (Fig. 3). The metastatic lymph node was classified as a macrometastasis in the final pathology report (1/28). Immunohistochemistry of the lymph node confirmed positivity for S-100 and Melan-A. The postoperative diagnosis was stage IIIC pT4bN1bM0 primary left breast skin melanoma. The patient is currently under regular follow-up.

Figure 2.

Surgery. (A, B) Left breast quadrantectomy and sentinel node biopsy were performed, followed by reconstruction using Holmström's thoracodorsal flap.

Figure 3.

Microscopy. Haematoxylin & Eosin staining. (A) 10X magnification: Cutaneous melanoma with infiltrating neoplastic cells containing melanin pigment (arrow). (B) 40X magnification: Melanoma cells forming infiltrating neoplastic nests with melanin pigment (arrowhead). (C) Immunohistochemistry: Melan-A positive.

Primary melanoma of the breast is a rare malignancy, representing 0.5% of all breast cancers. It is essential to exclude metastases in other regions of the body [1]. Surgical excision with adequate margins, up to 2 cm for Breslow thickness of 2 mm or greater, is the preferred treatment. Sentinel lymph node biopsy is recommended for invasive melanomas with ulceration [2]. Lymph node involvement is a significant prognostic factor, and lymphadenectomy is frequently advised. For locally advanced or metastatic disease, PD-1 immunotherapy is indicated. Prognosis is stage-dependent, with survival rates of 95% in stage I-II, 74% in stage III, and 35% in stage IV [3].

Funding statement

The case presented was entirely self-funded by the authors and did not receive external funding.

Ethical aspects and informed consent

The patient approved the written informed consent for publishing the presented case and the images of the attached photographs. We have the approval of the Ethics Committee of the Essalud High Complexity Hospital – Virgen de la Puerta.

Author contributions

JRTV & EFYQ Preparation, creation and presentation of the work, manuscript writing and supervision. OBG and GLC supply pathological anatomy materials and manuscript writing. JRTV and EFYQ Approval of manuscript submission.