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Chin Med J (Taipei) 1997;60:113-6.
Division of General Surgery, Mackay Memorial Hospital, Taipei, Taiwan, R.O.C.
A case is reported of splenic epidermoid cyst discovered in a 21-year-old female. The lesion was shown by abdominal ultrasonography and computed tomography to be 14x12x8 cm in size and to contain serous fluid in the lumen. The spleen was easily removed by surgery. Histopathologically, the epidermoid cyst was composed of a loosely fibrous wall and a single layer interior lining of flattened or low-cuboidal epithelium, without skin appendages. The remaining splenic tissue showed mild congestive change with thickened sinusoidal stroma. Most splenic cysts have presented with symptoms related to both the size of the mass and compression of an adjacent organ. Potential complications include hemorrhage, infection, and rupture of the splenic cyst. Splenectomy is recommend to eradicate symptoms produced by the cyst and to prevent potential complications.
[Chin Med J (Taipei) 1997;60:113-6.]
Keywords: splenectomy , splenic epidermoid cyst
Received: March 31, 1996.
Accepted: June 19, 1997.
Address reprint requests to: Hung-Bun Lam, Division of General Surgery, Mackay Memorial Hospital, No. 92, Sec. 2, North Chung San Road, Taipei, Taiwan, R.O.C.
Splenic cysts are rare [1]. They may be parasitic, most frequently caused by Echinococcus granulosus, or nonparasitic. Nonparasitic cysts are divided into true cysts, which exhibit an epithelial lining or and secondary, so-called false cysts or pseudocysts which do not show an epithelial lining and are thought to result from trauma or hemorrhage. Pseudocysts are more frequent than epithelium-lining cysts [1]. Their wall is made up of dense collagenous tissue which often contains deposits of calcium and hemosiderin. If remnants of an epithelial lining can be identified, the cysts should be classified as epidermoid cysts[1]. True cystic tumors include hemangiomas, lymphangiomas, epidermoid and dermoid cysts. Of these, hemangiomas are the most common and dermoid cysts, the least. Epidermoid cysts comprise 10% of nonparasitic splenic cysts [2].
A 21-year-old female had complained for two years of intermittent, dull, wandering pain at the left costal margin . Further, constipation, nausea and body weight loss of about two kilograms had been noted the month just past. There was no history of trauma. Physical examination revealed a visible bulging mass in the left upper quadrant. A smooth, firm, nontender mass was palpable extending 2 cm to the right of the midline and 6 cm below the left costal margin. Laboratory examinations showed normal results. Chest roentenography showed left hemidiaphrag-matic elevation. Plain abdomen roentenography showed the stomach was markedly medially displaced by the enlarged spleen. Ultrasonography demonstrated a cystic lesion in the left upper quadrant with some echogenic content (Figure 1). Abdominal computed tomography found that the huge cystic lesion with splenic compression was displacing many organs (Figure 2).
Exploratory laparotomy with splenectomy was performed. On gross examination, a large spleen (19 x 14 x 8 cm in size) (Figure 3), with a single cyst was identified. A cystic space was seen measuring up to 14 cm in the greatest dimension. About 1500 ml of turbid-yellow fluid was drained from the cyst. The net weight of the spleen was 100 gm. Microscopically, the sections showed a picture of epidermoid cyst composed of a loosely fibrous wall and an interior lining of single layer of flattened or low-cuboidal epithelium, without skin appendage. The remaining splenic tissue showed mild congestive change with thickened sinusoidal stroma (Figure 4). The post-operation course was uneventful, and the patient was discharged on the eighth postoperation day.
True cysts of the spleen are uncommon. The epidermoid cyst is the rarest, representing 10% of the benign, nonparasitic cysts [2]. Robbins reported a series of 42,327 autopsies over a 25-year period, which revealed only 32 patients with diagnosis of splenic cyst [3,4]. Subsequent isolated case reports have appeared in the literature [4].
In 1953, Fowler published a collective review to include 265 cases of nonparasitic splenic cysts [4]. Until 1978, approximately 600 surgical and autopsy cases of such cysts have been reported in the world literature [4]. Three-fourths are post traumatic pseudocysts. The remainder are true cystic tumors.
Epidermoid cysts comprise 10% of nonparasitic splenic cysts [4] . In Taiwan, no report of epidermoid cyst has been found in the literature.
Some classify splenic cysts according to presumed etiology or pathogenesis [4]. In 1958, Martin simplified the clinical classification to primary and secondary, descriptive terminology now preferred by most authors [4].
By pathological classification, the presence of a cellular cyst lining, defines a true cyst; these represent about one-fourth of nonparasitic benign cysts. False cysts which have fibrous tissue lining comprise the remainder. The pseudocyst, is thought to result from trauma, hemorrhage or infarction. The relationship of trauma in the pathogenesis of splenic cysts is still unclear [4].
Clinically, the symptoms are produced by a bulking mass which compresses the adjacent visceral just as a benign cystic tumor of the spleen. Because the slow growing rate of epidermoid cysts present initially with rather vague symptoms: such as epigastric fullness, dull pain and left upper quadrant enlargement, such lesions are most commonly discovered within the second and third decades of life. This is compatible with the literature description [4].
Physical examination may have only negative findings, or a simple left upper quadrant mass. The mass, occasionally mildly tender, can make the left hemidiaphragmatic movement poor, and lower lobe atelectasis or pneumonia may result [4]. Fortunately, no pulmonary distress was presented in this patient.
Routine laboratory tests including hematological studies and liver function tests are usually normal [4]. Chest and abdominal roentgenogram are usually normal; however, calcification may be present within the lesion mass [4] . Calcifications commonly show in hydatid cysts and are also note in post-traumatic or post-inflammatory pseudocysts, but are rare in true splenic cysts [4] . The radiological diagnosis of splenic cysts has been based on indirect evidence mentioned by King et al. [5]: (1) displacement of the stomach medially; (2) left diaphragmatic elevation . Those were found in this patient's plain abdominal roentenogram.
Some invasive diagnostic studies such as splenography, splenic cystography, and selective splenic arteriography are arranged to achieve accurate preoperative diagnosis, particularly if there is suspicion of malignancy [4]. Ultrasonography can provide useful information to show if the mass is a cyst or solid. Abdominal computed tomography study can localize the mass and provide its relationship to other adjacent organs.
Although no epithelium is present histogenetically in the normal spleen, splenic epidermoid cyst is thought to be a tumor arising from embryonic inclusion of aberrant ectodermal and entodermul epithelium in the developing spleen, or, from, metaplastic mesodermal cells [6].
As to treatment method, surgical intervention is indicated if the splenic mass produces troublesome symptoms, as in the present patient, in whom symptoms were resolved dramatically post-operation . Splenectomy is a method for large asymptomatic cysts. Other possible procedures include aspiration alone, incision and drainage [4]. However, splenectomy remains a relatively safe procedure, associated with few complications and avoiding any future problems [4]. Potential complications of huge splenic cyst include rupture with peritonitis, rupture with massive hemorrhage, infection, abscess formation and transdiaphragmatic perforation with pleural effusion or empyema [2] . If splenic epidermoid cyst rupture or hemorrhage occurs, mortality becomes obvious [7]. Laparoscopic marsupialization may increase the chance of the cystic content spilling into the peritonea. Especially in hydatid disease, there is a risk of leakage into the peritoneal cavity and either anaphylaxis or cyst implantation. On the other hand, laparotomy is preferable to laparoscopy in a condition of unconfirmed cystic nature or cystic origin. However, splenectomy is curative, and remains a good choice for safe treatment in cases of epidermoid splenic cyst.
Copyright: 1997, Chinese Medical Association (Taipei)