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Journal of the Anatomical Society of India

Splenunculi- Report of Three Cases

Author(s): Harsh Mohan; Amanjit; Bhardwaj, S., Handa, U.

Vol. 51, No. 1 (2002-01 - 2002-06)

Department of Pathology, Govt. Medical College & Hospital, Sector - 32-A, Chandigarh, INDIA.

Abstract

Splenunculi or accessory spleen is a congenital ectopic splenic tissue arising during embryologic period of development. Most of the splenunculi are asymptomatic and discovered incidentally but sometimes they become symptomatic and even mimic tumour when present within the organ. It is important for the surgeon to recognize splenunculi at the time of splenectomy for haematological causes because if they are left behind they will undergo hyperplasia and cause recurrence of disease. We present three incidental cases of splenunculi diagnosed on histopathologic examination.

Key words : Splenunculi, ectopic spleen, splenosis.

Introduction :

Ectopic splenic tissue results from two etiologies : (i) accessory spleen or splenunculi (congenital); and (ii) splenosis (acquired). Accessory spleen represents congenital ectopic splenic tissue and is found in 10 - 44% of all necropsies (Al Ahmadi et al. 1998). Its most common location is hilum of the spleen and can occur in contiguity with tail of the pancreas. Mesentery, omentum and peritoneum are the rare sites. We present three cases of splenunculi, all presenting as incidental findings, one localized in omentum, second located on serosa of small intestine and third an incidental finding in neonate autopsy localized in hilum of the spleen.

Case Reports:

Case - 1 : A 53 year old male presented with history of post-prandial fullness of abdomen. CT scan revealed retroperitoneal mass with intra- abdominal extension. Per-operatively there was a large mesenteric tumour infiltrating the greater omentum and epiploicae coli. Tumour was resected and end to end anastomosis of small intestine was done.

Histopathologic examination:

On gross examination the specimen included small intestine along with mesenteric tumour measuring 18 x 14 x 8 cm and omentum. There was a gray brown/tan nodule in the omentum measuring 2x 1cm. On microsopic examination the mesenteric tumour revealed non-Hodgkin's lymphoma with infiltration in the omentum and lymph nodes. Gray brown nodule in the omentum showed well-formed capsule, trabeculae, red pulp and white pulp (formed by lymphoid follicles with central arteriole) of the spleen. Thus this showed the structure of normal spleen and diagnosed as splenunculi.

Case - 2 : A 48 year male presented with symptoms of abdominal pain and distension. X-ray abdomen revealed multiple air fluid levels. Clinical impression was of acute intestinal obstruction. Per- operatively there were dense adhesions causing intestinal obstruction and a gray brown nodule on the serosal surface of small intestine. Lysis of adhesions was done and the nodule was excised.

Histopathologic Examination:

On gross examination the excised tissue was a gray brown encapsulated nodule measuring 1 X 1 X 0.5 cm. Microscopically it showed well-encapsulated splenic parenchyma composed of white and red pulp, diagnosed as accessory spleen/splenunculi. Case - 3 : Neonatal autopsy of 3 day old baby was done. Baby weighed 2750gm with crown rump length of 33.5cm. External examination revealed Potter's facies and imperforate anus.

Autopsy Examination:

The spleen weighed 10 gm and measured 4x 2.5 x 1 cm while there was an accessory spleen in the hilum measuring 0.5 cm. There was hypoplasia of left kidney. All other viscera were grossly unremarkable.Microscopically accessory spleen showed structure similar to the main spleen so diagnosed as splenunculi. Other organs did not reveal any significant pathologic change.

Discussion:

Splenunculi or accessory spleen is a congenital condition seen in 10 - 44% of necropsies (Al Ahmadi et al.1998). An accessory spleen arises from the side of the dorsal mesogastrium during embryological period of development as a result of imperfect fusion of separate splenic masses.Most often there is one accessory spleen (85%) sometimes two (14%) and rarely three or more (1%). Their size is not larger than 2cm in diameter. The most common location is hilum of the spleen in gastrosplenic ligament (50%), but may be found behind the tail of pancreas (30%) or rarely within greater omentum of the stomach, mesentery of the small intestine,mesocolon, pancreas (Hayward et al.1992), Kidney (Servadio et al. 1994) and pelvis as an adnexal mass (Azar et al. 1993). Most of the splenunculi are asymptomatic and are discovered incidentally by abdominal ultrasound, CT scan or laparotomy during the investigation of another problem. In a few cases they become symptomatic causing abdominal pain due to torsion and infarction (Raichuk et al.1994).

Accessory spleen needs to be distinguished from splenosis which is an acquired condition associated with splenic trauma or surgery having incidence of 67% in these patients (Fleming et al. 1976). Splenosis presents as numerous nodules (as many as 400) in any intraperitoneal or extraperitoneal location. Splenosis nodules receive their blood supply from newly formed arteries penetrating the capsule.

Histologically it is possible to differentiate splenunculi from splenosis. Splenunculi have well formed capsule, hilum, trabeculae, white pulp with Malpighian follicles having central arteriole and red pulp whereas splenosis nodule are surrounded by capsule but malpighian follices with a central arteriole are not formed.

Splenunculi are important in haematological disorders for which splenectomy is the treatment of choice. If surgeon is not able to locate or remove them at the time of splenectomy, they will undergo hyperplasia and cause recurrence of the disease. Accessory spleens resemble normal spleen in structure and in immunologic functions. So in splenectomy for non-haematologic causes accessory spleens should be preserved to prevent infection and sepsis after splenectomy.

In addition splenunculi can mimic tumours of the kidney, pancreas and pelvis. Thus it is important to identify splenunculi either by CT scan or by 99m Tc heat-denatured red blood cell scan and confirmed by histopathologic examination to avoid misdiagnosis.

References :

  1. Al Ahmadi, M., Brundage, S., Brody, F., Jacobs, L. and Sakier (1998): Splenosis of the mesoappendix,a case report and review of literature. Journal of Royal College of Surgery Edinburgh 43: 200-202.
  2. Azar, G.B., Awwad, J. T. and Muffarrij,I. K. (1993) : Accessory spleen presenting as adnexal mass. Acta Obstetrica Gynecologica Scandnevica 72 587 - 588.
  3. Fleming, C. R. Dickson, E.R. and Harrison,E.G. (1976) Splenosis; autotransplantation of splenic tissue. American Journal of Medicine 61 : 414 - 419.
  4. Hayward, I., Mindelzun,R.E. and Jeffrey, R.B. (1992) : Intrapancreatic accessory spleen mimicking pancreatic mass on CT scan. Journal of Computerized Assisted Tomography 16 : 984-985.
  5. Raichuk, I.E., Chesakov,S. A., Niirchenko,I.y., Gerich, F. N., Kukuriku, E. V. and Bukree, V. M. (1994) : Torsion of accessory spleen Klin Khir. 10 : 64.
  6. Servadio, Y., Leibovitch, I., Aprer, S., Mor, Y. and Goldwasser, B. (1994) : Symptomatic heterotopic splenic tissue inleft renal fossa. European urology. 25: 174-76.
Missing Image

1. Photomicrograph showing red pulp and white pulp (lymphoid follicle with central arteriole) of splenincule parenchyma (H&E, X100).

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