Cutaneous metastasis as the first manifestation of occult malignant breast neoplasia*

Cutaneous metastases from primary internal malignancies represent 0.7-9% of patients with cancer. We report a 65-year-old female patient referred for evaluation of normochromic papules on the trunk and upper limbs that had been present for three months. A skin biopsy revealed diffuse cutaneous infiltration by small round cell tumors. Immunohistochemistry was positive for AE1/AE3, CK7, estrogen receptor and mammaglobin. The final diagnosis was cutaneous metastasis of occult breast cancer, since the solid primary tumor was not identified. The location of the primary tumor can not be determined in 5-10% of cases. In these cases, 27% are identified before the patient’s death, 57% at autopsy, and the remaining 16% can not be located.


INTRODUCTION
Cutaneous metastasis is defined as a neoplastic lesion affecting the dermis or the subcutaneous tissue that originates from another primary tumor. 1 Three basic patterns of metastasis mechanisms are reported: mechanical tumor stasis (anatomical proximity and lymphatic drainage), organ-specific (selective affinity of tumor cells to a specific organ), and nonselective (independent of mechanical and organ-specific factors). 1 Malignant neoplasms that most commonly metastasize to the skin include breast cancer, colon cancer, melanoma, lung cancer, ovary cancer, sarcomas, and cervical cancer. 1 In most cases, cutaneous metastasis develops after the diagnosis of the primary internal malignancy and late in the course of the disease. An interval of five years from the initial diagnosis to the skin metastases is common. 2 0.7-9% of patients with cancer develop skin metastasis, which is considered a rare dermatological event. 2,3 However, with the increased incidence of internal cancer, dermatologists may be the first to discover the disease. 2 A high index of clinical suspicion is essential for the diagnosis of cutaneous metastatic lesions. 3

CASE
Who was referred to our institution for evaluation of asymptomatic papules and nodules on the trunk and upper limbs that had been present three months before the consultation. The patient was unable to report the initial morphology or changing pattern of the lesions. She also reported weight loss, which was not measured, and asthenia. Remarkable personal history included anemia treated with ferrous sulfate and a sectorectomy of a benign left breast lump eight years before -which was anatomopathologically confirmed.
The patient was G4P3A1 and had been in menopause for 16 years.
She denied alcohol abuse, smoking, or remarkable family history.
The lesions were slightly movable, 0.3-1 cm in diameter, located on the arm root, chest and back. We also observed a linear pearl-col-    Positive H. pylori • Normal chest X-ray, mammography, tomography of the abdomen/pelvis, and colonoscopy.
2005 and identified no neoplasias. The patient was then referred to an oncologist for follow-up and chemotherapy. Unfortunately, she died 10 months after the diagnosis.

DISCUSSION
The frequency of cutaneous metastases has increased due to higher cancer survival rates and better therapeutic alternatives. 4  The most common sites of metastasis (75%) are the scalp, navel, chest wall, and abdomen, and in 75% of women, they occur on the chest and abdomen. In women, the most common primary malignancy is breast cancer (69%), which tends to metastasize later to the anterior thoracic wall. 3 10 Breast cancer immunohistochemistry reveals a cytokeratins pattern of CK7+/CK20-. Estrogens and progesterone receptors are markers that increase the detection sensitivity of breast cancers. 7 Despite the imaging techniques and immunohistochemistry, the primary tumor location cannot be determined in 5-10% of cases.
In general, patients with metastatic carcinoma of unknown primary site have a worse prognosis. In these patients, the primary tumor is only identified in 27% of cases before death; 57%, at autopsy; and for the remaining 16%, primary tumor can not be identified. 8 q