Pathological and Immunohistochemical Microscopy of Natural Cases of Canine and Feline Neoplastic Mammary Lesions

Mammary cancer is the second most common tumor worldwide. Small animal mammary neoplasms provide an outstanding model to study cancer in humans, as tumors in both share a similar environment, histopathologic features, and biological behavior. This study aims to investigate the percentage and microscopy of breast tumors in affected dogs and cats; its relationship to breed, age, and sex; and the immunohistochemical expression of estrogen receptor (ER), progesterone receptor (PR), Ki-67, and cytokeratin 8. Twenty-four females (12 dogs and 12 cats) and one male were examined from February 2018 to February 2020. The highest percentage of mammary neoplasia from the highest to the lowest manifested as tubular carcinoma, leiomyosarcoma, fibroadenoma, and cystic papillary carcinoma. The current study reported the second micropapillary invasive carcinoma in a male cat and the third lipid-rich carcinoma in a female cat. Although tubular carcinoma was the most common mammary neoplasm in cats, leiomyosarcoma was the most common in dogs. The immunohistochemical staining revealed diffuse and intense cytoplasmic immunoreactivity for cytokeratin 8 in lipid-rich carcinomas. However, moderate expression of ER in benign tumors and slight to moderate ER expression in malignant mammary lesions were reported. On the contrary, there was a negative PR expression in benign lesion. It could be concluded that a close relationship between ER expression and nuclear antigen Ki-67 was found.

Canine Mammary Carcinoma With Vacuolated Cytoplasm: Glycogen-Rich Carcinoma, a Histological Type Distinct From Lipid-Rich Carcinoma

Lipid-rich carcinoma is a rare histotype of canine mammary tumors with cytoplasmic vacuolation. In humans, glycogen-rich carcinoma, secretory carcinoma, and myoepithelial neoplasms are included in the differential diagnosis for lipid-rich carcinoma. The aim of the study was to investigate the existence of histotypes other than lipid-rich in canine mammary carcinomas with vacuolated cytoplasm using a diagnostic algorithm based on histopathology, histochemistry, immunohistochemistry, and ultrastructure and to evaluate the molecular phenotype of these neoplasms. Ten mammary carcinomas were collected, histologically reviewed, and subjected to histochemistry (PAS, PAS with diastase, Alcian blue, Sudan III [1 case], and Congo red [1 case]); immunohistochemistry for CK19, CK5/6, CK14, p63, calponin, vimentin, ER, PR, and HER2; and transmission electron microscopy (TEM). Cytokeratin immunolabeling demonstrated the epithelial origin of all tumors. Sudan III and TEM confirmed the diagnosis of lipid-rich carcinoma in 8 tumors (one amyloid-producing). One tumor was reclassified as a glycogen-rich carcinoma based on PAS reactivity that was diastase-labile, and a second tumor was reclassified as a carcinoma-and-malignant myoepithelioma based on the differentiation markers. Lipid-rich carcinomas were basal-like (5/8), null-type (2/8), and luminal A phenotype (1/8). The glycogen-rich carcinoma was basal-like, while the carcinoma-and-malignant myoepithelioma was luminal A. Vacuolated morphology of neoplastic cells in canine mammary carcinoma can indicate either a neoplasm of luminal epithelial origin with cytoplasmic lipid or glycogen, or vacuolated neoplastic suprabasal myoepithelial cells. Glycogen-rich carcinoma is a novel histological type that should be considered in the differential diagnosis for canine mammary carcinomas with vacuolated cytoplasm.

Lipid-rich carcinoma of male breast in Chinese: a case report and literature review

Lipid-rich carcinoma of the breast is a rare variant of breast cancer, especially in males. Herein we report a case occurring in a 54-year-old male patient, who presented with a noticed painless, pea-sized lump in his left breast. Clinical examination and mammography suggested malignancy. Subsequent modified radical mastectomy revealed the diagnosis of lipid-rich carcinoma. To our knowledge, this subtype of mammary carcinoma is unprecedented in Chinese males in literature.

Lipid-rich carcinoma of the breast: A report of two cases and a literature review

Lipid-rich carcinoma of the breast is extremely rare with no standard guidelines for treatment with poor patient prognosis. In the present study, the clinical features, imaging results, pathology, immunohistochemistry, treatment and prognoses of two patients with lipid-rich carcinoma of the breast were analyzed. Two patients were admitted to the Yantai Yuhuangding Hospital Affiliated to the Medical College of Qingdao University (Yantai, Shandong, China) for examination of a palpable mass in the breast. Enlarged lymph nodes were found in the axilla of each patient. The results of mammography and echography imaging suggested the presence of malignancy. A modified radical mastectomy was performed in each patient, and pathological examination revealed atypical large vacuolated cells arranged in clusters and confirmed lipid-rich carcinoma and lymph node metastases. The tumor tissue of patient one was immunohistochemically positive for estrogen receptor (ER), p53, p120 and E-cadherin, and negative for progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER-2), with a Ki-67 labeling index of 50%. The tumor tissue of patient two was immunohistochemically positive for p53, and negative for ER, PR, HER-2 and cytokeratin 5/6, with a Ki-67 labeling index of 30%. Post-surgery, patient one was administered chemotherapy for six cycles, radiotherapy and endocrine therapy in the form of anastrozole. Patient two was administered three cycles of chemotherapy without radiotherapy. Subsequent to being followed up for 25 months and 13 months, respectively, there was no evidence of recurrence or distant metastasis in patient one or two, respectively.