Accessory spleen

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Accessory spleen
Other namesSupernumerary spleen, splenule, splenunculus
CT scan of an accessory spleen.jpg
CT scan of an accessory spleen (circular object in center of image) between the spleen and left kidney.
Specialty Medical genetics   OOjs UI icon edit-ltr-progressive.svg

An accessory spleen is a small nodule of splenic tissue found apart from the main body of the spleen. Accessory spleens are found in approximately 10 percent of the population [1] and are typically around 1 centimetre in diameter. They may resemble a lymph node or a small spleen. They form either by the result of developmental anomalies or trauma. [2] They are medically significant in that they may result in interpretation errors in diagnostic imaging [2] or continued symptoms after therapeutic splenectomy. [1] Polysplenia is the presence of multiple accessory spleens rather than one normal spleen.

Contents

Causes and locations

Accessory spleen
Details
Identifiers
Latin splen accessorius, lien accessorius
TA98 A13.2.01.022
TA2 5177
FMA 16028
Anatomical terminology

Accessory spleens may be formed during embryonic development when some of the cells from the developing spleen are deposited along the path from the midline, where the spleen forms, over to its final location on the left side of the abdomen by the 9th–11th ribs. The most common locations for accessory spleens are the hilum of the spleen and adjacent to the tail of the pancreas. They may be found anywhere along the splenic vessels, in the gastrosplenic ligament, the splenorenal ligament, the walls of the stomach or intestines, [3] [4] the pancreatic tail, [5] [6] the greater omentum, [7] [8] the mesentery, [9] the renal fossa, [10] [11] or the gonads and their path of descent. [12] The typical size is approximately 1 centimeter, but sizes ranging from a few millimeters up to 2–3 centimeters are not uncommon. [2]

Splenogonadal fusion can result in one or more accessory spleens along a path from the abdomen into the pelvis or scrotum. The developing spleen forms near the urogenital ridge from which the gonads develop. The gonads may pick up some tissue from the spleen, and as they descend through the abdomen during development, they can produce either a continuous or a broken line of deposited splenic tissue. [12]

Splenosis is a condition where foci of splenic tissue undergo autotransplantation, most often following physical trauma or splenectomy. Displaced tissue fragments can implant on well vascularized surfaces in the abdominal cavity, or, if the diaphragmatic barrier is broken, the thorax. [13] [14]

Significance

Accessory spleens may undergo hypertrophy after splenectomy Very rarely, it may cause bleeding (pictured). Hypertrophic accessory spleen with hematoma.jpg
Accessory spleens may undergo hypertrophy after splenectomy Very rarely, it may cause bleeding (pictured).

If splenectomy is performed for conditions in which blood cells are sequestered in the spleen, failure to remove accessory spleens may result in the failure of the condition to resolve. [1] During medical imaging, accessory spleens may be confused for enlarged lymph nodes or neoplastic growth in the tail of the pancreas, [5] gastrointestinal tract, adrenal glands or gonads. [2]

Related Research Articles

<span class="mw-page-title-main">Pancreas</span> Organ of the digestive system and endocrine system of vertebrates

The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins and fats in food entering the duodenum from the stomach.

<span class="mw-page-title-main">Spleen</span> Internal organ in all vertebrates

The spleen is an organ found in almost all vertebrates. Similar in structure to a large lymph node, it acts primarily as a blood filter. The word spleen comes from Ancient Greek σπλήν (splḗn).

<span class="mw-page-title-main">Duodenum</span> First section of the small intestine

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In mammals it may be the principal site for iron absorption. The duodenum precedes the jejunum and ileum and is the shortest part of the small intestine.

<span class="mw-page-title-main">Splenectomy</span> Surgical removal of the spleen

A splenectomy is the surgical procedure that partially or completely removes the spleen. The spleen is an important organ in regard to immunological function due to its ability to efficiently destroy encapsulated bacteria. Therefore, removal of the spleen runs the risk of overwhelming post-splenectomy infection, a medical emergency and rapidly fatal disease caused by the inability of the body's immune system to properly fight infection following splenectomy or asplenia.

<span class="mw-page-title-main">Hemangiosarcoma</span> Medical condition

Hemangiosarcoma is a rapidly growing, highly invasive variety of cancer that occurs almost exclusively in dogs, and only rarely in cats, horses, mice, or humans. It is a sarcoma arising from the lining of blood vessels; that is, blood-filled channels and spaces are commonly observed microscopically. A frequent cause of death is the rupturing of this tumor, causing the patient to rapidly bleed to death.

<span class="mw-page-title-main">Splenomegaly</span> Medical condition

Splenomegaly is an enlargement of the spleen. The spleen usually lies in the left upper quadrant (LUQ) of the human abdomen. Splenomegaly is one of the four cardinal signs of hypersplenism which include: some reduction in number of circulating blood cells affecting granulocytes, erythrocytes or platelets in any combination; a compensatory proliferative response in the bone marrow; and the potential for correction of these abnormalities by splenectomy. Splenomegaly is usually associated with increased workload, which suggests that it is a response to hyperfunction. It is therefore not surprising that splenomegaly is associated with any disease process that involves abnormal red blood cells being destroyed in the spleen. Other common causes include congestion due to portal hypertension and infiltration by leukemias and lymphomas. Thus, the finding of an enlarged spleen, along with caput medusae, is an important sign of portal hypertension.

<span class="mw-page-title-main">Pancreaticoduodenectomy</span> Major surgical procedure involving the pancreas, duodenum, and other organs

A pancreaticoduodenectomy, also known as a Whipple procedure, is a major surgical operation most often performed to remove cancerous tumours from the head of the pancreas. It is also used for the treatment of pancreatic or duodenal trauma, or chronic pancreatitis. Due to the shared blood supply of organs in the proximal gastrointestinal system, surgical removal of the head of the pancreas also necessitates removal of the duodenum, proximal jejunum, gallbladder, and, occasionally, part of the stomach.

<span class="mw-page-title-main">Splenic vein</span> Vein that drains blood from the spleen, stomach and pancreas

In human anatomy, the splenic vein is a blood vessel that drains blood from the spleen, the stomach fundus and part of the pancreas. It is part of the hepatic portal system.

<span class="mw-page-title-main">Splenic injury</span> Injury to the spleen

A splenic injury, which includes a ruptured spleen, is any injury to the spleen. The rupture of a normal spleen can be caused by trauma, such as a traffic collision.

<span class="mw-page-title-main">Annular pancreas</span> Medical condition

Annular pancreas is a rare condition in which the second part of the duodenum is surrounded by a ring of pancreatic tissue continuous with the head of the pancreas. This portion of the pancreas can constrict the duodenum and block or impair the flow of food to the rest of the intestines. It is estimated to occur in 1 out of 12,000 to 15,000 newborns. The ambiguity arises from the fact that not all cases are symptomatic.

<span class="mw-page-title-main">Extramedullary hematopoiesis</span> Medical condition

Extramedullary hematopoiesis refers to hematopoiesis occurring outside of the medulla of the bone. It can be physiologic or pathologic.

<span class="mw-page-title-main">Splenic infarction</span> Medical condition

Splenic infarction is a condition in which blood flow supply to the spleen is compromised, leading to partial or complete infarction in the organ. Splenic infarction occurs when the splenic artery or one of its branches are occluded, for example by a blood clot.

<span class="mw-page-title-main">Hemosuccus pancreaticus</span> Medical condition

Hemosuccus pancreaticus is a rare cause of hemorrhage in the gastrointestinal tract. It is caused by a bleeding source in the pancreas, pancreatic duct, or structures adjacent to the pancreas, such as the splenic artery, that bleed into the pancreatic duct, which is connected with the bowel at the duodenum, the first part of the small intestine. Patients with hemosuccus may develop symptoms of gastrointestinal hemorrhage, such as blood in the stools, maroon stools, or melena, which is a dark, tarry stool caused by digestion of red blood cells. They may also develop abdominal pain. It is associated with pancreatitis, pancreatic cancer and aneurysms of the splenic artery. Hemosuccus may be identified with endoscopy (esophagogastroduodenoscopy), where fresh blood may be seen from the pancreatic duct. Alternatively, angiography may be used to inject the celiac axis to determine the blood vessel that is bleeding. This may also be used to treat hemosuccus, as embolization of the end vessel may terminate the hemorrhage. However, a distal pancreatectomy—surgery to remove of the tail of the pancreas—may be required to stop the hemorrhage.

Spleen transplantation is the transfer of spleen or its fragments from one individual to another. It is under research for induction of immunological tolerance for other transplanted organs. Success has been achieved in rodent models. Recently, evidence has been obtained for a tolerogenic effect of a spleen transplant in miniature swine. Also, the spleen harbors primitive hematopoietic progenitor cells. Spleen transplantation has been performed on humans with mixed results.

<span class="mw-page-title-main">Wandering spleen</span> Medical condition

Wandering spleen is a rare medical disease caused by the loss or weakening of the ligaments that help to hold the spleen stationary.

<span class="mw-page-title-main">Blunt splenic trauma</span>

Blunt splenic trauma occurs when a significant impact to the spleen from some outside source damages or ruptures the spleen. Treatment varies depending on severity, but often consists of embolism or splenectomy.

<span class="mw-page-title-main">Splenogonadal fusion</span> Medical condition

Splenogonadal fusion is a rare congenital malformation that results from an abnormal connection between the primitive spleen and gonad during gestation. A portion of the splenic tissue then descends with the gonad. Splenogonadal fusion has been classified into two types: continuous, where there remains a connection between the main spleen and gonad; and discontinuous, where ectopic splenic tissue is attached to the gonad, but there is no connection to the orthotopic spleen. Patients can also have an accessory spleen. Patients with continuous splenogonadal fusion frequently have additional congenital abnormalities including limb defects, micrognathia, skull anomalies, Spina bifida, cardiac defects, anorectal abnormalities, and most commonly cryptorchidism. Terminal limb defects have been documented in at least 25 cases which makes up a separate diagnosis of splenogonadal fusion limb defect (SGFLD) syndrome.

<span class="mw-page-title-main">Ectopic pancreas</span> Medical condition

An ectopic pancreas is an anatomical abnormality in which pancreatic tissue has grown outside its normal location and without vascular or other anatomical connections to the pancreas. It is a congenital disease and is also known as heterotopic, accessory, or aberrant pancreas.

Splenosis is the result of spleen tissue breaking off the main organ and implanting at another site inside the body. This is called heterotopic autotransplantation of the spleen. It most commonly occurs as a result of traumatic splenic rupture or abdominal surgery. Depending on the location of the spleen, the new piece usually implants in another part of the abdominal cavity. Single case reports also describe splenosis in the thoracic cavity, in subcutaneous tissue, in the liver or in the cranial cavity. Splenosis must be distinguished from the presence of additional spleens, which are innate and are the result of differences in embryological development. Additionally, splenosis must be differentiated from malignant tumors which may look similar when imaged.

<span class="mw-page-title-main">Spleen pain</span> Human pain from the area of the spleen

Spleen pain is a pain felt from the left upper quadrant of the abdomen or epigastrium where the human spleen is located or neighboring.

References

  1. 1 2 3 Moore, Keith L. (1992). Clinically Oriented Anatomy (3rd ed.). Baltimore: Williams & Wilkins. p. 187. ISBN   978-0-683-06133-8.
  2. 1 2 3 4 Gayer G; Zissin R; Apter S; Atar E; Portnoy O; Itzchak Y (August 2001). "CT findings in congenital anomalies of the spleen". British Journal of Radiology. 74 (884): 767–772. doi:10.1259/bjr.74.884.740767. PMID   11511506.
  3. ↑ Wang G, Chen P, Zong L (February 2014). "Accessory spleen arising from the gastric fundus mimicking gastrointestinal stromal tumor following splenectomy: A case report". Exp Ther Med. 7 (2): 349–351. doi:10.3892/etm.2013.1415. PMC   3881060 . PMID   24396402.
  4. ↑ Almazeedi S, Alhaddad E, Al-Khithr T, Alhunaidi M (2017). "Incidental gastric accessory spleen during laparoscopic sleeve gastrectomy". Int J Surg Case Rep. 36: 119–121. doi:10.1016/j.ijscr.2017.05.022. PMC   5447567 . PMID   28558346.
  5. 1 2 Kim SH; Lee JM; Han JK; Lee JY; Kim KW; Cho KC; Choi BI (March–April 2008). "Intrapancreatic Accessory Spleen: Findings on MR Imaging, CT, US and Scintigraphy, and the Pathologic Analysis". Korean J Radiol. 9 (2): 162–174. doi:10.3348/kjr.2008.9.2.162. PMC   2627219 . PMID   18385564.
  6. ↑ Bostancı EB, Oter V, Okten S, Küçük NO, Soydal C, Turhan N, Akoglu M (November 2016). "Intra-pancreatic Accessory Spleen Mimicking Pancreatic Neuroendocrine Tumor on 68-Ga-Dotatate PET/CT". Arch Iran Med. 19 (11): 816–819. PMID   27845553.
  7. ↑ Zhang C, Zhang XF (September 2011). "Accessory spleen in the greater omentum". Am. J. Surg. 202 (3): e28–30. doi:10.1016/j.amjsurg.2010.06.032. PMID   21784408.
  8. ↑ Gill N, Nasir A, Douglin J, Pretterklieber B, Steinke H, Pretterklieber M, Cotofana S (2017). "Accessory Spleen in the Greater Omentum: Embryology and Revisited Prevalence Rates". Cells Tissues Organs (Print). 203 (6): 374–378. doi:10.1159/000458754. PMID   28420007. S2CID   3680876.
  9. ↑ Ruiz-Tovar J, Ripalda E, Beni R, Nistal J, Monroy C, Carda P (2009). "Hypersplenism caused by an accessory spleen mimicking an intra-abdominal neoplasm: report of a case". Surg. Today. 39 (9): 818–20. doi:10.1007/s00595-008-3919-z. PMID   19779782. S2CID   38549930.
  10. ↑ Servadio Y, Leibovitch I, Apter S, Mor Y, Goldwasser B (1994). "Symptomatic heterotopic splenic tissue in the left renal fossa". Eur. Urol. 25 (2): 174–6. doi:10.1159/000475275. PMID   8137861.
  11. ↑ Azar GB, Awwad JT, Mufarrij IK (October 1993). "Accessory spleen presenting as adnexal mass". Acta Obstet Gynecol Scand. 72 (7): 587–8. doi:10.3109/00016349309058171. PMID   8213112. S2CID   46645715.
  12. 1 2 Chen S–L; Kao Y–L; Sun H–S; Lin W–L (November 2008). "Splenogonadal Fusion". Journal of the Formosan Medical Association. 107 (11): 892–5. doi: 10.1016/S0929-6646(08)60206-5 . ISSN   0929-6646. PMID   18971159.
  13. ↑ Abu Hilal M; Harb A; Zeidan B; Steadman B; Primrose JN; Pearce NW (January 5, 2009). "Hepatic splenosis mimicking HCC in a patient with hepatitis C liver cirrhosis and mildly raised alpha feto protein; the important role of explorative laparoscopy". World Journal of Surgical Oncology. 7 (1): 1. doi: 10.1186/1477-7819-7-1 . PMC   2630926 . PMID   19123935.
  14. ↑ Madjar S; Weissberg D (October 1994). "Thoracic splenosis". Thorax. 49 (10): 1020–1022. doi:10.1136/thx.49.10.1020. ISSN   0040-6376. PMC   475241 . PMID   7974296.
  15. ↑ W. Richard Webb; Wiliam E. Brant; Nancy M. Major (2014). Fundamentals of Body CT, Fundamentals of Radiology (4 ed.). Elsevier Health Sciences. p.  242. ISBN   9780323263580.
  16. ↑ Note: The case is possibly splenosis rather than an accessory spleen:
    Maki, Takehiro; Omi, Makoto; Ishii, Daisuke; Kaneko, Hiroyuki; Misu, Kenjiro; Inomata, Hitoshi; Tateno, Masatoshi; Nihei, Kazuyoshi (2015). "Spontaneous hemorrhage from splenic tissue 13 years after total splenectomy: report of a case". Surgical Case Reports. 1 (1): 91. doi: 10.1186/s40792-015-0099-0 . ISSN   2198-7793. PMC   4593983 . PMID   26943415.
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