a. Proliferation of neoplastic tissue with large ulceration; Mammary adenocarcinoma

b. Simple tubular adenocarcinoma with large areas of necrosis (most of feline mammary adenocarcinomas are simple carcinomas).

c. Feline mammary adenocarcinomas are very aggressive neoplasms. They are initially locally invasive, but metastize early to regional lymph nodes and further. Distant metastases are also common and include lungs, pleura, liver and, occasionally diaphragm, adrenals, kidneys, heart; skeletal metastases are rare and they localize (contrary to the behavior of this neoplasm in dogs and humans) within the distal limb where they produce lysis; ocular involvement has also been described. The size of the tumor is perhaps the most important prognostic factor. Neoplasms > 3 cm, have a post-surgical survival 4-9 months; neoplasms 2-3 cm, have a post-surgical survival up to two years; neoplasms < 2 cm, have a post-surgical survival more than 3 years. The type of surgery performed and histologic grading are the next important prognostic indicators.