A case of a giant mass in the lumbar region of a newborn calf.

The present report describes a newborn calf with spina bifida that presented with a giant mass of the lumbar region, as well as subsequent gross, histological, and immunohistochemical examinations. A malformed Japanese black calf (estimated weight = 20 kg) was euthanized immediately after birth. A gross evaluation revealed a giant mass (approximately 60 cm × 30 cm × 15 cm) covered by the hair coat in the lumbar region and connected with the hair coat of the trunk. The mass surface was divided by a deep polygonal groove and externally resembled a lobulated kidney. Histology and immunohistochemistry revealed that the giant mass comprised a vessel, bronchiolus lined with cuboidal epithelium, and small alveolus. Bone bleaching revealed various abnormalities, including spina bifida, vertebral fusion, vertebral deformity, vertebral malformation, vertebral scoliosis, and coxal bone malformation. Following a suggestion that the giant lumbar region mass was occupied by lung tissue, this case was considered to involve an asymmetric conjoined duplicitas that resulted in a very rare dichotomous spondylosis malformation.