Foley G L, Valentine B A, Kincaid A L
Department of Pathology, New York State College of Veterinary Medicine, Cornell University, Ithaca, NY.
Vet Pathol. 1991 Sep;28(5):363-9. doi: 10.1177/030098589102800503.
In a retrospective study, cutaneous melanocytic tumors from 18 horses, less than 2 years old, were examined histopathologically and clinical follow-up requested. Melanocytomas (benign melanomas) occurred in a variety of breeds and in horses of varied coat color. The age of the horses at the time of biopsy ranged from 3 weeks old to 2 years old. Four melanocytomas were congenital, 11 melanocytomas were acquired by 1 year of age, and three were acquired prior to 2 years of age. Of the 18 horses, five were male, and 13 were female. All tumors were solitary and located on the legs or trunk; none were in the perineal region. Ulceration of the overlying epidermis was common. Tumors were generally localized and were not encapsulated. The tumors had a variety of cell patterns ranging from sheets, to streams, or nests of melanocytes. Cellular morphologic findings also ranged from epithelioid, to a mixture of epithelioid and spindle cells or to a spindle pattern. The nuclei were large and euchromatic, especially in the epithelioid cells. Several tumors had moderate cellular pleomorphism and binucleate cells. Mitotic activity was generally low (less than 1/high-powered field), but was readily detected (1-2/high-powered field) in bleached sections of four cases. Melanin pigmentation varied from mild to heavy. Melanophages were admixed with the tumor cells or in the adjacent tissue. Follow-up information was obtained on 15/18 horses and revealed that 14/15 horses were free of recurrence following excision. One neoplasm, that was poorly demarcated and had a spindle cell pattern, was not completely resected and continued to grow. These melanocytic tumors in young horses are distinct from melanomas in aged horses in their location, epithelial involvement, and age of horses affected. The majority of these tumors appear to be benign and share features of melanocytic nevi of human beings.
在一项回顾性研究中，对18匹年龄小于2岁的马的皮肤黑素细胞肿瘤进行了组织病理学检查，并要求进行临床随访。黑素细胞瘤（良性黑色素瘤）发生于各种品种和不同毛色的马匹。活检时马匹的年龄范围为3周龄至2岁。4例黑素细胞瘤为先天性，11例在1岁时获得，3例在2岁前获得。18匹马中，5匹为雄性，13匹为雌性。所有肿瘤均为单发，位于腿部或躯干；会阴区域均未发现。覆盖其上的表皮溃疡很常见。肿瘤通常局限，无包膜。肿瘤有多种细胞模式，从黑素细胞的片状、条索状到巢状。细胞形态学表现也从上皮样细胞到上皮样细胞与梭形细胞的混合或梭形模式。细胞核大且呈常染色质，尤其是在上皮样细胞中。一些肿瘤有中度细胞多形性和双核细胞。有丝分裂活性通常较低（每高倍视野少于1个），但在4例病例的脱色切片中很容易检测到（每高倍视野1 - 2个）。黑色素沉着从轻度到重度不等。噬黑素细胞与肿瘤细胞混合或存在于相邻组织中。对18匹马中的15匹获得了随访信息，结果显示15匹马中有14匹在切除后无复发。有一个边界不清且呈梭形细胞模式的肿瘤未完全切除并继续生长。这些幼马的黑素细胞肿瘤在位置、上皮受累情况以及受影响马匹的年龄方面与老年马的黑色素瘤不同。这些肿瘤中的大多数似乎是良性的，并且具有人类黑素细胞痣的特征。
