Vascular Hamartoma in the Uterus of a Female Sprague-Dawley Rat with an Episode of Vaginal Bleeding

Abstract

An annular, reddened lesion with mild serosal hemorrhage and no tumorous mass formation was detected in the right uterine horn of a 37-weekold female Sprague-Dawley rat that had postpubertal vaginal bleeding. Histological examination revealed prominent proliferation of the endometrium, which occupied the uterine lumen. There were numerous aberrant vascular spaces filled with erythrocytes, proliferation of stromal cells, and inflammatory infiltrates including hemosiderin-laden macrophages in the endometrium. These vasculatures extended into the myometrium, and in a transverse section of the lesion, they were mostly distributed throughout the circumference of the uterus. They were irregular in shape and interconnected, forming a large vascular sinus and anastomosing reticular channels. In the area with serosal hemorrhage, the muscular layer covering the large irregular vascular space had undergone degeneration and necrosis. The lining cells of the vasculatures were often plump, and they protruded into the lumen and were arranged in a tombstone or hobnail manner. Immunostaining revealed that these cells were positive for von Willebrand factor and CD34. The aberrant vasculatures were not accompanied by pericytes or muscular layer, although a discontinuous muscular wall was present around some of them. From these results, the uterine lesion was diagnosed as a vascular hamartoma.

Cerebral Vascular Hamartoma In a Campeiro Bulldog

“…However, angiomatosis secondary to lymphedema are accompanied by characteristic hypoplasia of the deep lymphatic vessels and markedly dilated lymphatics, which were not seen in the current case. Capillary hemangiomas do not show neuropile present between vascular structures [19,28]. One of the main features of VH is that its component vessels are separated from each other by normal neural parenchyma [9,14,19].…”

Cutaneous vascular hamartoma in a lamb

“…Microscopically, the nodule was characterised by a marked proliferation of well-differentiated endothelial cells arranged within the vascular structures with multiple lobes extending from the https://doi.org/10.17221/111/2019-VETMED (Braun et al 2011). Cases of dogs with hamartoma in the brain have also been reported (Sakurai et al 2011), as has one case in the uterus of a rat (Shirota et al 2013). In these cases, vascular changes were similar to those described in the sheep in this study, all of them with lesions characterized by irregular growth of neoformed blood vessels.…”

“…Sometimes, hamartomas are difficult to differentiate from vascular neoplasms, the main indication being limited growth. Structures such as large well-defined vessels and lack of mitotic activity are suggestive of hamartoma (Bildfell et al 2002;Shirota et al 2013).…”

Scientific and Regulatory Policy Committee (SRPC) Points to Consider

“…Observation of such findings may warrant exclusion of the affected individuals from the study. EDSP Workshop participants felt that microscopic data from control animals should be maintained in searchable databases (along with the literature) to assist in the interpretation if such findings occur (Keenan et al 2009; Shirota et al 2013). Concordance of estrous cyclicity data: Microscopic evaluation of female reproductive tissues should be conducted taking into account the final in-life stage of the estrous cycle as determined from the vaginal cytology obtained on the day of necropsy.…”

“…Observation of such findings may warrant exclusion of the affected individuals from the study. EDSP Workshop participants felt that microscopic data from control animals should be maintained in searchable databases (along with the literature) to assist in the interpretation if such findings occur (Keenan et al 2009;Shirota et al 2013). 3.…”