K Kjossev, J Losanoff, N Velitchkov, E Belokonski
diaphragm, hydatid cyst, surgery
K Kjossev, J Losanoff, N Velitchkov, E Belokonski. Hydatid Cyst Of The Diaphragm: A Case Report And Review Of The Literature. The Internet Journal of Thoracic and Cardiovascular Surgery. 2002 Volume 6 Number 1.
Hydatid cysts of the diaphragm (also known as extrapulmonary intrathoracic cysts) are found occasionally, with less than 100 cases reported in the literature. We report such a case and update the diagnostic and therapeutic aspects of the condition.
An 18-year-old male patient was diagnosed with a right lower intra-thoracic mass. CT revealed this to be hydatid cysts. At thoracotomy, a conglomerate of three hydatid cysts originating from the diaphragm was found. The cysts were managed by endocystectomy and unroofing of the fibrous capsules. A retrospective analysis of fifty published reports of diaphragmatic hydatidosis (1960-2001) was performed together with a complimentary review of the Bulgarian literature.
A total of 66 cases constitute the basis of this review estimating an incidence of 0.5-1.6%. The cysts were primary in 69.8%, the right hemidiaphragm was the most common site (72.5%), and associated hydatidosis (38.7%, predominantly hepatic and/or pulmonary) was frequently encountered. The preoperative diagnosis of diaphragmatic hydatid cysts demands a high index of suspicion and utilization of imaging methods. Treatment is only surgical and proceeds through transthoracic (83.8%) or transabdominal (16.2%) approaches. Radical surgery includes total cystectomy or pericystectomy, used in 53.7%; deroofing of the fibrous capsulae is the preferred, less traumatic procedure.
Hydatid cysts should be considered in the patients with preoperative imaging data indicating cystic lesions adjacent to the diaphragm. Surgery provides the only chance of cure.
Hydatid disease has been known since the time of Hippocrates, and it still represents a major health problem in endemic regions. In Bulgaria where the condition's incidence is 3.3 patients per 100.000 of the population , hydatidosis is included in the differential of space-occupying lesions. The condition is found predominantly in the liver (70-75%) and lungs (20-25%) ; these organs are affected simultaneously up to 18% of patients . Uncommon hydatid cyst (HC) locations include the peritoneal cavity (10-16%), kidneys (1.5-4%), spleen (3%), brain (3%), musculoskeletal system (0.5-4%), heart (2 %), and retroperitoneum (1%) [4-6]. Primary HCs of the diaphragm (HCDs) are extremely rare. We describe recent experience with this unusual HC location and provide a world literature update, with review of the Bulgarian literature.
An 18-year-old male presented with right hypochondralgia of 10 days duration. His past medical history was significant for a liver HC, treated surgically when the patient was 16. No specific medical treatment had been given. The patient has had no further symptoms and his serological and ultrasound (US) follow-up remained unremarkable.
The patient's current physical exam and laboratory tests were unremarkable. Indirect hemagglutination for hydatid disease was positive to a dilution of 1:600. A plain chest x-ray film demonstrated an oval mass in the right hemichest, possibly originating from the diaphragm (Figure 1).
Abdominal US and CT scan showed three hydatid cysts of the liver dome (Figure 2a, b).
A diagnosis of recurrent liver hydatidosis in the hepato-diaphragmatic recess was made. The surgical approach proceeded through a midline laparotomy. The triangular and right coronary ligaments were dissected along with multiple postoperative infra- and suprahepatic adhesions. Intraoperative exam of the liver including US revealed no hepatic disease. The liver was rotated to the left. Three diaphragmatic cysts protruded in the right subphrenic space. The operative field was isolated by multiple packs soaked in 20% sodium chloride solution.
The cysts were aspirated, injected with 20% sodium chloride for 20 minutes, aspirated again, and opened. No intracavitary daughter cysts were found; the diaphragm muscle was intact. The cysts were deroofed and left to heal secondarily. The subdiaphragmatic space was drained and the abdomen closed. The postoperative period was uneventful; a chest x-ray taken at 10 days postoperatively demonstrated a normal diaphragmatic contour (Figure 3).
Review Of The Literature
Our recent experience preliminary data about the condition's rarity prompted us to perform a retrospective literature review. Fifty reports of HCDs were published during the past 40 years (1960-2001) in the international literature [7-57]. An independent review of the Bulgarian literature [11, 15, 25, 39, 43, 49, 50, 56, 57] is summarized in Table 1.
The diaphragm is usually secondarily affected by a variety of cystic lesions originating in the thoracic or abdominal cavities; these may be congenital including mesothelial, bronchogenic, and fibrous, and acquired including traumatic and parasitic [9, 52]. Primary cysts from each of these categories (35%) are rare [54, 58]. In this context, HCDs are occasionally found, with less than 100 cases reported. HCDs are also known as extrapulmonary intrathoracic hydatid cysts . They were first described in 1927 by Gabrielle . In 1960, Gamov  reported 2400 intrathoracic HCs, 7 of them diaphragmatic (0.3%). Forty-two HCD reports were published before 1965, 11 of them in the Russian literature . In 1973, Guedj et al.  reported 1000 intrathoracic HCs including 12 HCDs (1.2%). In 1978, Lazar et al.  surveyed 61 HC patients with no hepatic or pulmonary cysts including 6 HCDs (9.8%). More recent series include Daali et al's report  15 patients who had intramuscular HCs, 7 of them had HCDs (46.6%), and Kabiri et al's study  analyzing 27 HCDs out of 2332 thoracic HC cases (1.16%).
The path of hydatid larvae reaching the diaphragm appears puzzling. They can affect the diaphragm primarily or secondarily [31, 39].
HCDs resulting from visceral HC rupture in either the abdominal or thoracic cavities represent a
HCDs are covered with pleura or peritoneum. Three varieties have been described including subpleural, subperitoneal, and intramuscular . This classification is theoretical, however. During the HC growth, the cyst causes local ischemia and muscle erosion  and produces peripulmonary or perihepatic adhesions [42, 57]. These, together with the negative intrapleural pressure facilitating intrabronchial HC rupture , and occasional massive cyst calcifications, cause tissue distortion and make an exact anatomic cyst localization difficult.
Clinical presentation and diagnosis
Patients with primary HCDs are asymptomatic or complain of right hypochondralgia, which results from tissue compression. The onset of complaints may be insidous sometimes, with non-specific symptoms such as fatigue, fever, nausea, cough, and allergy [7, 15, 41].
To make the diagnosis of a HCD depends on the investigator's high index of suspicion. It is not rare to discover a cyst during a prophylactic x-ray examination and the plain chest x-ray may give a clue to the diagnosis [43, 45, 56]: an impaired hemidiaphragm mobility or elevation, pleural effusion, or calcifications have been described as relatively specific radiologic HCD signs [13, 30]. A pulmonary basal shadow with burred or erased diaphragm borders also rises suspicion for a HC lesion but has been considered non-specific HCD . A recent review on the US role in HC diagnosis  concluded that US is a useful primary imaging modality, but stressed it's inability to distinguish HCDs from HCs of the liver dome.
The CT's diagnostic power has been considered equal to US , however, CT displays the abdominal topography better and provides more information about the HC size, multiple and daughter cysts, and the neighboring organs' condition [8, 27]. CT is sensitive in detecting HC calcifications but does not distinguish between HCDs and HCs adjacent to the diaphragm. Transdiaphragmatic HC spread may be observed with CT, but the diaphragmatic gap is difficult to visualize .
MRI is important when imaging HCs with atypical CT appearance . The method's advantage is based on the superior chest wall and diaphragm delineation. However, characteristic MRI features have not been described for HCDs.
Other radiologic procedures such as radionuclide scintigraphy and diagnostic pneumothorax or pneumoperitoneum, although widely used in the past [7, 41], are currently ignored in favor of the more sensitive imaging methods outlined above. Hydatid serology has a diagnostic yield of 50% and its role remains supplementary .
The treatment of HCDs is only surgical. The operative strategy is directed by the cyst's nature and the patient's general condition. Surgery is guided by: 1) Total removal of the parasite; 2) Prevention of recurrence; 3) Sound diaphragm repair, and 4) Treatment of associated lesions [3, 51, 62].
Because of a great variability in HC size, location, and natural history, there are no uniform surgical guidelines . The surgical approach to HCD demands flexibility because adjacent organs from two body cavities might be affected. There are three access routes to HCDs: thoracic, abdominal, and combined. The decision to choose each of these depends mainly on the patient's past HC history and on the coexistence of HCs in other locations . The most favored incision is lateral or posterolateral thoracotomy . Coexisting pulmonary HCs can be dealt with during a one-stage procedure . Intraabdominal HCs further require laparotomy, especially if the cyst is located beneath the hepatic dome or if there are multiple cysts .
Protection of the operative field is essential. Except for radical surgical excision where the parasite is removed without opening the cyst, use of local scolicidals is mandatory. After evacuation of the cyst contents the remaining cavity is cleaned and lavaged with a scolicidal. Based on our experience with more than 200 surgical cases of liver hydatidosis during the last 10 years, we advocate the use of hydrogen peroxide, 5% silver nitrate, and 20% sodium chloride.
Total cyst resection including a margin of normal diaphragm (also called total cystectomy) gives the best chance for cure since it removes the parasite and creates no hydatid dissemination . The indications of this approach are limited to single, small cysts however. The remaining diaphragm defect is usually difficult to reconstruct, and prosthetic materials may be needed to prevent diaphragmatic hernia [41, 51]. En-block (closed method) total cysto-pericystectomy, removing the pericyst without opening the cyst, is feasible in superficial HCDs where dissection in a correct plane of cleavage leaves thin fibrous membrane on the diaphragm surface. This procedure eliminates any risk of accidental fluid spillage or need for irrigation of the residual cyst cavity with scolicidal agents, which have caused serious complications . Open total cysto-pericystectomy is safe and valid option for management of large, multiple or adhering to neighboring organs HCDs .
Unroofing, or partial cysto-pericystectomy is especially advantageous if the cyst walls are fibrous and rigid, or if the cyst location does not permit a reliable closure (33). Simple endocystectomy includes removal of the cyst contents leaving the fibrous layer intact; the residual cavity is then obliterated with sutures (capitonnage). This method's disadvantages include dead space and a greater risk of recurrence . HCDs do not constitute a homogenous entity and the surgical procedures used depend on their location, size, and number. Our literature review confirmed that the transthoracic access to HCDs has been preferred by most investigators; both the radical and conservative procedures have proved appropriate (Table 3).
There are few reports of video-assisted thoracic surgery (VATS) treatment of thoracic hydatidosis [7, 67]. None of the HCDs reviewed was treated by VATS.
HCD should be considered in patients with preoperative imaging data indicating cystic lesions adjacent to the diaphragm. The only treatment method is surgery, with radical excision of the cyst serving the best chance of cure. Conservative surgical methods such as cystectomy should be restricted to large HCD.
Dr. Kirien Kjossev
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