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Paper text:
a 56-year - old gentleman presented under the surgical team with left upper quadrant pain and mild anemia ( hb 11.2 gm / dl ) .
he reported feeling well aside from intermitted left upper quadrant pain and denied any weight loss .
he underwent a ct scan which showed a 10    10    9  cm rounded lesion within the spleen with small areas of central calcification ( fig.1 ) .
there was no evidence of lymphadenopathy or any other neoplastic process from the ct scan .
bone marrow biopsy showed active trilineage hemopoiesis without any evidence of lymphoma or other infiltrative neoplastic process . computed tomography ( ct ) .
this showed paucicellular fibrosis with medium - caliber vessels embedded in fibrous tissue showing signs of obliteration and/or recanalization .
he subsequently underwent splenectomy to characterize these splenic lesions as splenic biopsy itself was not completely diagnostic .
resected spleen ( 175    110    95  mm ) weighed 578  g. it contained a central bulky stellate mass of white compact tissue ( 50    40    45  mm ) , surrounded by multiple poorly defined hard dark - brown nodules ( fig.2 ) .
microscopically , the center of the lesion consisted of almost acellular hyaline , whereas the peripheries comprized macro - nodular aggregates of round angiomatoid structures , each composed of a chaotic meshwork of capillary - like vessels in the middle ( cd34 + , cd31 + , cd8 ) , rimmed by a band of collagen - rich connective tissue , and scant smooth muscle cells .
the appearances were diagnostic for sclerosing angiomatoid nodular transformation of the spleen ( sant ) , a very rare entity first recognized in 2004 , distinct from much more frequent hamartomas and angiomas .
in retrospect , features of this lesion were also seen in the core needle biopsy , which , however , was hardly diagnostic on its own .
sclerosing angiomatoid nodular transformation was originally described in 2004 by martel et  al 1 .
radiologically , they present as solitary , round , lobulated mass which is centrally hypodense with peripheral - enhancing portions .
contrast ct / mri scan shows heterogeneously hypo - enhancing lesion during arterial and venous phase with an early peripheral - enhancing radiating lines and delayed enhancement of the central area due to fibrous tissue .
mri appearances on t1-weighted images have been described as  spokes wheel pattern  3,4 .
it is noted that these lesions are fdg - avid . in few reported cases where pet ct is employed ,
fdg - avid multiple splenic nodules with a  prunes on bread  appearance in the maximum - intensity - projection image ( mip image ) are seen . in sectional pet / ct images , a central cold area with peripheral increased fdg uptake in the splenic nodule
immunostaining of the vessels simulate the composition of normal splenic red pulp and features are different from angioma , hemangioma of the spleen .
myofibroblasts are highlighted within the nodules and endothelial lining cells are d2 - 40 negative supporting vascular over lymphatic origin .
vessels in the angiomatoid nodular are the combination of three different types : capillaries ( cd34+/cd8/cd31 + ) , small veins ( cd34/cd8/cd31 + ) , and sinusoids ( cd34/cd8+/cd31 + ) .
some cells in sant are cd68 + and sma+ 1,6 . differential diagnoses of splenic lesions include both benign and malignant disease .
it is difficult to rule out other benign pathological conditions of the spleen such as inflammatory pseudotumor or hamartoma using imaging modalities .
however , it may be possible to differentiate benign and malignant splenic lesions with a combination of clinical history and radiological modalities . asymptomatic patient with hyper echoic lesions
point toward benign , whereas patients with systemic symptoms and hypo echoic lesions on the scan should point toward possible malignant etiology .
however , nodular carcinomatous metastasis to spleen can not be sufficiently be diagnosed by imaging modalities alone .
although histological examination of the spleen is always employed to give the diagnostic yield , there is a debate if one should be subjecting an asymptomatic patient through a surgical procedure to obtain diagnosis .
there were diagnostic clues from splenic biopsy in our case , but the diagnosis of most of the published cases has been based on a splenectomy specimen .
suggests that good core biopsy can be used to distinguish sant from other lesions . however , there is a worry about risk of intra peritoneal seeding if the lesion biopsied proves to be angiosarcoma and other complications such as splenic rupture and bleeding are noted with splenic biopsy .
postulated that sant was a response to stromal proliferation and that the internodular zones were similar to inflammatory pseudotumor 1,7 .
sant may represent a hamartomatous transformation of splenic red pulp in response to an exaggerated nonneoplastic stromal proliferation . in majority of cases ,
sant - like changes may be occasionally seen in vicinity of splenic metastases , but there was no evidence of any malignant / metastatic process in this case .
key clinical messagesclerosing angiomatoid nodular transformation ( sant ) of spleen is a very rare benign entity with unknown etiology . here , we report this unusual case in a fit middle - aged gentleman and discuss various diagnostic modalities along with the management of this condition .