Other markers such as Calcitonin, CEA, PAX8 (variable and weak) [31], and the Congo red for amyloid, together with a triple-negative phenotype (ER-, PR-, HER2 score 0) can aid in diagnosing a breast metastasis from a medullary thyroid cancer,. The gene discussed is CALCA; the disease is medullary thyroid gland carcinoma.