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Introduction:
Cocoon is a covering of silk threads that some insects
make to protect themselves before they become adult.
Abdominal coccon is a peculiar morphologic entity
characterized by encasement of part or the whole of the
small bowel by a fibrocollagenic cocoon like case 1-3.  It is
a rare condition of unknown aetiology that primarily affects
adolescent girls living in tropical and subtropical regions4.
Abdominal cocoon usually presents as recurrent acute or
sub acute intestinal obstruction with or without a mass 3.
About 60 articles dealing with this topic was found in
Medline search till date 2. Here we report a case of
abdominal cocoon in a young girl with history of
intermittent colicky pain in right lower abdomen for about
a year. Clinically it was diagnosed as recurrent appendicitis.
Laparotomy was done and resection of the lump was
performed and the specimen was sent for histopathology
with a provisional diagnosis of intestinal tuberculosis.

Case Report
A 15 year old girl from Narsingdi presented with a history of
intermittent colicky pain in the right lower abdomen for one
year. The pain aggravated after taking food. There had been
7 to 8 episodes of similar attack of pain during last one year
which was relieved by taking medications (homoepathic
drugs). She had a history of weight loss and occasional
fever. During her last attack she consulted a local physician.
Clinical diagnosis was recurrent appendicitis.  On
examination she was found anaemic, pulse rate was 68/min
and blood pressure was 100/70 mm Hg. Routine laboratory
tests revealed a total leucocyte count of 6500 cell/cmm,

Abdominal Cocoon – A Case Report with Short Review of Literature
Tamanna Choudhury1, Mohammed Kamal2
1Associate Professor, 2 Professor & Chairman, Department of Pathology, Bangabandhu Sheikh Mujib Medical University, Dhaka

Abstract:
Abdominal cocoon is a rare entity where there is encapsulation of the small bowel by a fibrous membrane causing
clustering of the bowel. The exact aetiology is unclear. We report a case of a 15 year old girl with a history of recurrent
colicky abdominal pain in the right lower abdomen. Clinical diagnosis was recurrent appendicitis. She underwent
laparotomy for appendicular lump. Histopathological examination of the resected lump grossly and histologically revealed
the features of abdominal cocoon.

Key Words:  Abdominal Cocoon, Sclerosing encapsulating peritonitis, Small bowel.

[BSMMU J 2009; 2(2): 81-84]

CASE REPORTS

Address of Correspondence: Dr. Tamanna Choudhury,  Associate
Professor, Department of Pathology,  Bangabandhu Sheikh Mujib
Medical University, Dhaka,  E-mail: ctamanna317@yahoo.com

polymorphonuclear leucocytes were 69% and lymphocytes
were 29%. Her haemoglobin was 12.6gm/dl and ESR was 10
mm and a normal urine analysis. Ultrasonogram (USG) of
the whole abdomen was done. There was a mixed echogenic
lump in the right iliac region (64mm X 43mm) which gave an
impression of appendicular lump. The whole abdomen was
otherwise normal. She was admitted to a local clinic and
underwent laparotomy in April 2009. On opening the
abdomen a huge mass was found in the terminal ileum.
Resection of the terminal ileum with caecum and proximal
part of the ascending colon was done followed by
ileocolonic anastomosis, as stated in the operation note.
Recovery of the patient was uneventful.

The surgical specimen was sent to the Department of
Pathology, BSMMU with a provisional diagnosis of
intestinal tuberculosis.On gross examination there was a
long loop of intestine measuring 26 cm in length. Central
portion of the loop was dilated measuring 10 cm in diameter
(Fig.-1), located 10cm from the proximal resection margin

Fig.-1: Gross view of the resected intestine



Review of literature
Abdominal cocoon is a rare condition 1,3-7 that refers to
total or partial encapsulation of the small bowel by a thick
fibrocollagenous membrane or cocoon like membrane  and
adhesions causing clustering of the bowel with local
inflammatory infiltrate leading to acute or chronic bowel
obstruction 1,3,6-8. Occasionally the large bowel, stomach,
liver or other abdominal organs may be involved 2,3,6 .

Historical background
Abdominal cocoon was first described in 1907 by
Owstchinnikow as peritonitis chronica fibrosa incapsulata
3. Brown et al. 9 described the condition as a complication
of long term treatment with beta adrenergic blocking
agents. The abdominal cocoon was first described and
named in 1978 by Foo et al.10Abdominal cocoon, a rare
condition primarily affects young females from tropical
and subtropical regions 4,7 but adult case reports from
temperate zones and in  both genders can be encountered
in literature 3,4,7. A Medline search revealed that in English
literature approximately 47 cases have been reported till
2006 4 . Another study reported about 60 articles dealing
with this topic found in Medline search 2.This condition
has been variously described as sclerosing peritonitis,
encapsulating peritonitis or sclerosing encapsulating
peritonitis (SEP) 5,11 .

Aetiological factors
Abdominal cocoon is of two types primary or idiopathic
and secondary 2,3,5,12. The primary or idiopathic abdominal
cocoon is a rare condition mainly described in young girls
from tropical regions2,3,12. To explain the aetiology and
the formation of the membrane of this condition a number
of hypotheses have been proposed. These include
retrograde menstruation with a superimposed viral
infection 1,3,4,8,10 retrograde peritonitis via fallopian tubes,
and cell mediated immunological damage incited by
gynaecological infection13. However none of these
hypotheses explain the characteristic age group, sex, and
geographical distribution of this disease and there is no
objective evidence to substantiate them 4.

Secondary abdominal cocoon has been reported following
long term use of the beta blocker practolol 9,14,15 or
associated with sarcoidosis, SLE, liver cirrhosis, chronic
ambulatory peritoneal dialysis (CAPD), intraperitoneal
instillation of drugs,  leiomyomata of the uterus, ovarian
endometriosis16 or tumours of the ovary, tuberculous
pelvic inflammatory disease 2,3,5,6,14.  These conditions
may predispose patients to peritoneal irritation and
inflammation, which as a final effect leads to peritoneal
fibrogenesis 3,6.

Fig.-2: Cut section of the dilated part of the intestine

and 6cm from the distal resection margin. Caecum or
ascending colon could not be identified. The serosa was
apparently unremarkable. On opening the dilated portion
showed multiple luminal structures clustered together and
covered by thick fibrous tissue. Majority had thickened
mucosa resembling intestinal mucosa and few had thin
mucosa (Fig.-2). The average diameter of the luminal
structures was about 2.5cm. Three lymph nodes were
found. Multiple sections were given from the luminal
structures including the lymph nodes. On microscopic
examination the sections from the luminal structures
revealed only lymphoid hyperplasia in the submucosa.
There was moderate infiltration of chronic inflammatory
cells in the serosa with fibrosis (Fig 3).  Lymph nodes
revealed features of reactive changes. There was no
evidence of granuloma or malignancy. The diagnosis was
‘Primary Abdominal Cocoon’.

Fig.-3: Microscopic section of the intestinal wall shows
lymphoid hyperplasia in the submucosa  (H & E X 200).
Inset shows microscopic section of the serosa showing
thickening with chronic inflammatory cell infiltration
(H & E X400)

Abdominal Cocoon – A Case Report with Short Review of Literature Tamanna Choudhury & Mohammed Kamal

82



Clinical features
Patients usually presents with features of acute/subacute
small bowel obstruction, symptoms of chronic obstruction,
progressive nausea and vomiting, weight loss and/or
colicky pain associated with an abdominal lump 2-4,6,7,16.
A preoperative diagnosis is almost never made and the
non specific and intermittent symptoms may result in delay
in diagnosis 4.

Most cases are diagnosed incidentally at laparotomy
although a preoperative diagnosis is purported feasible
by a combination of barium follow through  (concertina
pattern or cauliflower sign and delayed transit of contrast
medium)3,5-7 and computed tomography of abdomen may
be more diagnostic 3demonstrating small bowel loops
congregated to the center of abdomen encased by a soft
tissue density mantle, peritoneal thickening, calcification,
peritoneal enhancement, small bowel tethering and
loculated fluid collection 1,5,6,8. USG  may show clumping
of bowel loops with the bowel surrounded by a thick rim
of  hypoechoic tissues 6. However, preoperative diagnosis
of abdominal cocoon requires a high index of clinical
suspicion 7, supported by clinical data and image findings
indicative of the condition16.

Clinicians must rigorously pursue a preoperative diagnosis,
as it may prevent a ‘surprise’ upon laparotomy and
unnecessary procedures for the patient such as bowel
resection 7. Most cases were diagnosed when a laparotomy
was performed for obstructive symptoms 9. The
characteristic findings is that of the encasement of the
whole or part of the small bowel by a thick shiny membrane,
aptly simulating cocoon. The loops of the small bowel
remain stuck together by filmy soft adhesions separated
easily by blunt or sharp dissections from the cocoon4,12.
Histopathological examination of the encapsulating
membrane shows thickened fibrocollagenous tissue with
or without lymphocytic and plasma cell infiltration 2-5.
Regional lymph nodes demonstrate non specific reactive
hyperplasia 10,12. The final diagnosis of abdominal cocoon
is usually made based on intraoperative and histological
findings 1.

Management
As conservative management often fails 3 surgery remains
the cornerstone in the management of abdominal cocoon
4. Surgery includes careful dissection and excision of the
thick sac with release of small intestine and adhesiolysis
of small bowel loops 3-5,7,16 which leads to complete
recovery 1,4,7. Resection of bowel is unnecessary and
increases morbidity and mortality  and is indicated only if
it is nonviable 7.

Differential diagnosis
Abdominal cocoon or sclerosing encapsulating peritonitis
(SEP) may be confused with a developmental anomaly
where the whole of the small bowel is encased in a thin
membrane. The clinical symptoms differ from those of the
abdominal cocoon in that the patients are mostly
asymptomatic and the findings are incidental and late in
life5,12.

Prognosis
The prognosis of abdominal cocoon after surgery seems
excellent and no recurrence has been described4,17,18.

Conclusion:
Although abdominal cocoon is a rare entity, it can be
diagnosed preoperatively as it may have a distinct
appearance on barium follow through and CT of the
abdomen and also with high index of clinical suspicion. In
this case however only USG was done which gave an
impression of an appendicular lump.

This case report intends to raise an awareness and enable
earlier preoperative diagnosis and prevent unnecessary
bowel resection as careful dissection and excision of the
thick sac with release of small intestine and adhesiolysis
of small bowel loops leads to complete recovery.

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