2018 Volume 51 Issue 5 Pages 357-364
A 32-year-old woman was referred to our hospital because of melena, and ischemic colitis was diagnosed. On abdominal CT, a round-shaped mass of 38 mm in the spleen was incidentally found showing central hypodense and peripheral enhancement in the early phase, and finally enhanced toward its center creating what is called a “spoke wheel-like pattern” in the delayed phase. MRI showed the tumor was gradually heterogeneously enhanced compared with normal splenic parenchyma, and we therefore preoperatively suspected sclerosing angiomatoid nodular transformation of the spleen (SANT) but did not rule out other diagnoses, including malignancy. We performed laparoscopic splenectomy. Microscopically, the tumor was composed of multiple, variably sized nodules separated by α-smooth muscle actin immunopositive myofibroblastic cells, with three types of vascular structure; cord-type capillaries, sinusoid type spaces, and small vessels. These findings yielded a diagnosis of SANT. Spindly and ovoid cells for fibrosclerotic stroma are immunohistochemically positive for IgG4 plasma cells, and especially in the marginal area, the IgG4/IgG ratio in the tumor was increased to over 40%. To the best of our knowledge, this case appears to be extremely rare with SANT meeting the diagnostic criteria for IgG4-related disease.
