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 centimeter 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]

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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