|Year : 2011 | Volume
| Issue : 2 | Page : 135-137
Hydatid cyst in rectus abdominis muscle in a child: An unusual occurrence
Chiranjib Nag1, Mrinalkanti Ghosh2, Taraknath Ghosh3, Shamik Dey4, Pallabhi Maji5
1 Department of General Medicine, Burdwan Medical College, Burdwan, India
2 Department of Radiology, Burdwan Medical College, Burdwan, India
3 Department of Paediatrics, Burdwan Medical College, Burdwan, India
4 Memorial Nursing Home, Ajha Pur, Burdwan, India
5 Tirupati Diagnostic Centre, Burdwan West Bengal, India
|Date of Web Publication||31-Oct-2011|
Department of General Medicine, Burdwan Medical College, Burdwan, West Bengal, 713101
| Abstract|| |
Hydatid cysts usually involve the liver; extrahepatic localization is reported in 11% of all cases of abdominal hydatid disease. Cyst at unusual localization includes kidney, heart, spleen, pancreas and brain. Isolated involvement of muscle is also rare in children. Here is a case of hydatid cyst in a female child involving the rectus abdominis muscle, which is a very rare presentation. There were no cysts in any other location. Serological tests were negative for cystic echinococcosis. The patient was operated on and the cyst was completely excised. The pathologic examination confirmed the diagnosis of hydatid cyst.
Keywords: Children, hydatid cyst, rectus abdominis muscle
|How to cite this article:|
Nag C, Ghosh M, Ghosh T, Dey S, Maji P. Hydatid cyst in rectus abdominis muscle in a child: An unusual occurrence. Trop Parasitol 2011;1:135-7
| Introduction|| |
Hydatid cyst, a parasitic disease of humans, is caused by a small cestode tapeworm Echinococcus granulosus, which is a natural habitat in the small intestine of dogs and other canids. Considering all age groups, liver is the most frequent (62%) site, followed by lung (20%).  Cysts at less-unusual localization include kidney, heart, spleen, pancreas, brain, bones and muscles.  But, in children, lung is a common site.  Isolated involvement of muscle is also rare in children. After a thorough search of the literature, we did not find a single case of hydatid cyst in rectus abdominis in a child, although few cases in have been reported in adults.  We are presenting one case of hydatid cyst in rectus muscle in a 4½-year-old girl child. The aim of this study is to report such rare case of hydatid cyst for this uncommon location without lung or other involvement in such a young age group.
| Case Report|| |
A 4½-year-old female child hailing from a rural area with poor socioeconomic background presented with a history of gradually increasing painless swelling of the left upper abdomen for the last 6 months duration. There was no history of associated fever, vomiting, pain abdomen and bladder and bowel abnormalities. The girl used to play with dogs and was reared up in an overcrowded, poor hygienic condition. All vaccines were taken as per the national schedule. General survey revealed no abnormality, except mild anemia. Anthropometric data also corresponded with the age of the child. Physical examination showed a firm globular mass, a non-mobile, non-tender parietal mass (diameter 7/6 cm), in the left hypochondrium. No organomegaly was noted. Other system examination revealed no abnormality. Ultrasonography (USG) examination revealed a well-defined cystic SOL with definite capsule and eccentric hyperechoic area and few echogenic materials within the cyst at the intramuscular location in the left hypochondrium within the left rectus sheath [Figure 1]. Computed tomography (CT) scan was also corroborating with the USG findings, and did not show any involvement of other areas or organs like lung and liver or kidney. Routine examination of the blood showed WBC-6800, P-53%, L-30%, E-12%, M-4%, B-1%, Hb% -9.6 gm and platelet-190000. The coagulation profile was normal. The chest X-ray and electrocardiogram were within normal limits. Imaging characteristics led us to rule out the existence of hydatid cyst, and a serological test (enzyme-linked immunosorbent assay for IgG of E. granulosus) was performed, which was found to be negative. Therefore, aspiration cytology was performed taking all precautions for easily accessible superficial mass for diagnosis. Microscopic examination of the aspirated material on H/E staining showed amorphous yellow granules suggestive of scolices of E.granulosus against an inflammatory background, which indicated the diagnosis of hydatid cyst with secondary infection [Figure 2]. The mass was then resected under general anesthesia with all precautions. The operating field was infiltrated with a hypertonic saline solution. Surgical excision was followed by medical treatment with Albendazole for 4 weeks post-operatively. The post-operative period was uneventful and the patient was discharged after 1 week. Histopahological examination of the surgical specimen revealed typical features of hydatid cyst characterized by an outer non-nucleated laminated gelatinous layer and an inner nucleated layer. During the last 3 months of follow-up, the child was well without any recurrence.
|Figure 1a: Smooth swelling of hydatid cyst in the rectus muscle at the left hypochondium in a girl child|
Figure 1b: Ultrasonography of the lump revealed a well-defined cystic SOL with definite capsule and eccentric hyperechoic area in the cyst at the intramuscular location in the rectus sheath, suggestive of hydatid cyst
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|Figure 2a: Fine needle aspiration cytology of the cyst showing amorphous yellow granules suggestive of scolex of the hydatid cyst|
Figure 2b: Histopathology of the cyst after excision shows typical features of hydatid cyst having an outer non-nucleated laminated gelatinous layer and an inner nucleated layer
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| Discussion|| |
Cystic hydatid disease is a parasitic infection caused by E. granulosus, characterized by cyst formation in different organs and tissues. It is a zoonosis and is transmitted from domestic and wild members of the canine family via parasite eggs to a variety of wild and domestic animal. In areas endemic for E.granulosus , the parasite is often acquired in childhood, but detection of the cyst requires many years by producing symptoms. Considering all age groups, liver is the most frequent (62%) site, followed by lung (20%).  Cyst at less-unusual localization includes kidney, heart, spleen, pancreas and brain. Bones and muscles are involved in only 4% of the cases.  But, in children, the lung is a common site.  Isolated involvement of the muscle is also rare in children. After a thorough search of the literature, we did not find a single case of hydatid cyst in the rectus abdominis muscle in such young children. In this respect, our case is a very unique one.
The larval stage of E. granulosus usually migrates through the blood and lymphatics to the primary target organs such as liver and lung after transforming from egg to oncosphere in the human intestine. Sometimes, few escape the hepatic filter and enter the systemic circulation and disseminate through systemic circulation and scatter to cause disease in the extraperitoneal sites like muscle, etc.  The extraperitoneal involvement is very rare,  and few authors have reported large series with extraperitoneal involvement by the disease process. Aydilin reported 14 cases with primary retroperitoneal hydrated cysts.  Here, hematological dissemination can explain the presentation of cyst in this unusual site of the rectus muscle. ,
From a clinical point of view, hydatid cyst takes many years to be detected for its usual position (liver, lung), but our case has been detected earlier as it was presented as a left hypochondrial mass. We tried to establish the nature of the SOL. USG is very helpful, and here it established the nature of the SOL as a cystic one. Calcified scolex was identified with definite capsule of the cyst in the intramuscular location of the left rectus sheath. Pre-operative CT scan reproducibly localized the lesion, with typical features of hydratid cyst with scolex, and it is sometimes more informative, particularly when the USG report is indeterminate. In our case, the CT finding is corroborative with the USG findings. We performed the ELISA test for IgG of E. granulosus for the confirmation of the diagnosis as, before operation, it is mandatory to establish the pathological nature of the cyst, particularly for the planning of the operation. ,
Serological test was proved to be unhelpful to support the diagnosis in our case as it became negative. At times, this test may not be useful in confirming the diagnosis of Echinococcosis as the false-negativity rate may be as high as 50%, which happened in our case. In indeterminate cases, fine needle aspiration cytology (FNAC) from the superficial lesion is recommended when pathological diagnosis is mandatory. In our case, a negative serological test put the patient for FNAC with all required precautions.  FNAC pathologically diagnosed it as hydatid cyst.
Surgical treatment with cyst excision and pericystectomy is appropriate for most of the patients. , Every attempt is made to avoid intraperitoneal spillage with cyst and cyst material to avoid secondary anaphylactic reaction.  In the present case, simple excision of the cyst was performed for this superficial, easily approachable mass without any complication. Surgical therapy may be followed by antihelminthic therapy as suggested by Tepetes et al.  In our case, as it is known that the patient belonged to an endemic region with poor hygienic socioeconomic status, we administered the antihelminthic drug to prevent recurrence, as recommended by some authors. 
| Acknowledgment|| |
The authors would like to thank Prof. Shyamal Mitraniyogi, Prof and Head, Department of Radiology, Burdwan Medical College and Hospital, for their expert comment in his field.
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[Figure 1], [Figure 2]