|Year : 2020 | Volume
| Issue : 2 | Page : 205-208
Neuroendocrine tumor in a lesser sac bronchogenic cyst – A hitherto unreported entity made rarer by concomitant hepatic hydatid cyst
Neha Bakshi1, Shashi Dhawan1, Pratishtha Sengar1, Ushast Dhir2
1 Department of Pathology, Sir Ganga Ram Hospital, Rajender Nagar, New Delhi, India
2 Department of Surgical Gastroenterology and Liver Transplantation, Sir Ganga Ram Hospital, Rajender Nagar New Delhi, India
|Date of Submission||17-Nov-2018|
|Date of Decision||05-Mar-2019|
|Date of Acceptance||09-Mar-2019|
|Date of Web Publication||17-May-2020|
Department of Pathology, Sir Ganga Ram Hospital, Rajender Nagar, New Delhi
Source of Support: None, Conflict of Interest: None
Intra-abdominal bronchogenic cysts are rare entities and only a handful of cases occurring within the lesser sac have been described. Further, the development of malignancy in a bronchogenic cyst is exceptional and one arising in a lesser sac has so far not been reported. We present herein an account of a 44-year-old man who presented with recurrent upper abdominal pain. Investigations revealed a mass in the lesser sac and a hydatid cyst in the liver. The histopathological examination of the excised mass showed bronchogenic cyst, with a neuroendocrine tumor of intermediate grade arising in its wall. Concomitant presence of hydatid cyst in the liver made this case even more unusual.
Keywords: Bronchogenic cyst, hydatid cyst, lesser sac, malignancy, management
|How to cite this article:|
Bakshi N, Dhawan S, Sengar P, Dhir U. Neuroendocrine tumor in a lesser sac bronchogenic cyst – A hitherto unreported entity made rarer by concomitant hepatic hydatid cyst. Indian J Cancer 2020;57:205-8
|How to cite this URL:|
Bakshi N, Dhawan S, Sengar P, Dhir U. Neuroendocrine tumor in a lesser sac bronchogenic cyst – A hitherto unreported entity made rarer by concomitant hepatic hydatid cyst. Indian J Cancer [serial online] 2020 [cited 2020 May 31];57:205-8. Available from: http://www.indianjcancer.com/text.asp?2020/57/2/205/284482
| » Introduction|| |
Bronchogenic cysts (BCs) are rare developmental aberrations originating from an abnormal budding of the primitive foregut between the third and seventh week of embryonic life. The majority of these are located in the mediastinum, and they are rarely reported in extra-thoracic locations such as the abdomen., Further, retroperitoneum is the most prevalent site of intra-abdominal BCs and BCs of the lesser sac are exceedingly rare., Most BCs remain asymptomatic or result in local symptoms due to infection, compression, and, rarely, hemorrhage or rupture. Malignant transformation within the cyst wall is exceptional., To the best of our knowledge, no case of neuroendocrine tumor arising in a lesser sac BC has been reported thus far in the literature. Our case also had a coexistent hydatid cyst in the liver, which makes this case even more unique as no such lesion has been previously reported.
| » Case Report|| |
A 44-year-old man presented with complaints of loose stools and recurrent abdominal pain for the past 6 months. The pain was mild, dull aching in nature and localized to the right upper abdomen without radiating to back. His previous medical and surgical history was insignificant, and physical examination was unremarkable. The computed tomography scan of the upper abdomen revealed a relatively well-defined, lobulated non-enhancing soft tissue density lesion in the superior recess of the lesser sac measuring 4.6 × 3.3 × 3.7 cm [Figure 1]a. Another well-defined encapsulated non-enhancing fluid density lesion was seen in the subhepatic region measuring 7.6 × 7.7 × 7.2 cm, with few imperceptible thin internal septations and calcification within it [Figure 1]b. A radiological impression of lesser sac mass (? nature) and hydatid cyst liver was made. Whole body 18F-FDG PET-CT imaging showed no evidence of any abnormal hypermetabolic focal uptake to suggest a primary neoplastic disease. Echinococcus antibody IgG (hydatid serology) was positive. Serum chromogranin A levels (assessed in view of diarrhea) were elevated at 188 ng/ml (biological reference interval <108 ng/ml). Exploratory laparotomy revealed a 5 × 4 × 3 cm sized mass in the lesser sac that was densely adherent to the superior border of pancreas and the retroperitoneum. Another 9 × 8 × 6 cm sized cystic lesion was present in segment VI of the liver, that was superficial and without any biliary communication. The excised lesser sac mass had a lobulated, grey-yellow largely solid cut surface with a cystic area at the periphery measuring 1.2 cm in diameter filled with yellow necrotic debris [Figure 2]a. The microscopic examination of the cyst revealed a pseudostratified ciliated columnar lining with areas of squamous metaplasia [Figure 2]b. The wall showed an organized structure with presence of fully developed cartilage and smooth muscle bundles replicating the histology of tracheobronchial structures [Figure 2]b and [Figure 2]c. There was no haphazard arrangement of the constituent components. There were no other mature or immature elements. The absence of any other elements and the organized structure of the cyst wall argued against teratoma. Areas of cyst rupture with chronic inflammation, hemorrhage, and cholesterol clefts were observed. Within the cyst wall, a solid tumor composed of nests, pseudoglandular spaces, and trabeculae of cells was seen [Figure 2]d. Tumor cells had bland, mildly pleomorphic nuclei, with salt and pepper chromatin, inconspicuous nucleoli and granular eosinophilic cytoplasm [Figure 2]e. Small foci of necrosis and few mitotic figures were present (1-2/10 high power fields). Tumor cells were positive for Cytokeratin. Cytokeratin expression was weaker in comparison to the very strong and diffuse synaptophysin and chromogranin positivity. Paraganglioma was ruled out by cytokeration positivity and S 100 negativity. Ki 67 proliferation index was 4–5%. The cyst lining was focally positive for cytokeratin and negative for synaptophysin, chromogranin, TTF1, and CDX2. There was no pancreatic tissue.
|Figure 1: A panel of photographs depicting: (a) Axial contrast enhanced computed tomography scan shows a well-defined round to oval lesion in the superior recess of the lesser sac in relation to the gastro-hepatic ligament (arrow). (b) Axial CECT scan shows a well-defined predominantly cystic lesion with areas of calcification in segment 6 of liver, suggestive of a hydatid cyst (arrow)|
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|Figure 2: (a-e) A panel of microphotographs depicting: (a) Cut surface of the excised lesser sac mass shows largely solid, lobulated, grey yellow appearance with a cystic area at the periphery filled with yellow necrotic debris. (b and c) Lesser sac cyst shows organized structure with pseudostratified ciliated columnar lining and mature cartilage (b), smooth muscle (c) in the wall. (d) Tumor in the cyst wall composed of cords, pseudoglandular spaces and nests of bland cells. (H and E; 4×), (e) Tumor cells show speckled chromatin, granular eosinophilic cytoplasm, and occasional mitosis. [H and E; ×40]. (f) Immunohistochemistry for synaptophysin shows strong diffuse positivity. [×20]|
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The excised liver cyst was grossly unilocular with a smooth, pearly white inner lining that was focally covered with necrotic debris. Sections showed a fibrous cyst wall, at places covered by eosinophilic laminated membrane [Figure 3]. Numerous refractile hooklets and calcified degenerated protoscolices were identified over the luminal surface [Figure 3] inset]. Liver parenchyma observed at the periphery was histologically unremarkable.
|Figure 3: Photomicrograph showing unremarkable liver parenchyma with a fibrous cyst wall focally covered by eosinophilic laminated membranes. [H and E; ×4. Inset shows refractile hooklets and degenerated protoscolices over the luminal surface]|
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A final diagnosis of neuroendocrine tumor (intermediate grade) arising in a lesser sac BC with hydatid cyst liver was made. The postoperative course was uneventful; the patient was discharged at 5th day postoperatively and has remained asymptomatic through serial follow-ups for the last 14 months. Serial serum chromogranin A levels remain within normal limits and repeat Ga-68-DOTANOC PET CT scan did not reveal any mass lesion.
| » Discussion|| |
First described by Meyer in 1859, BCs are congenital anomalies believed to arise from supernumerary or abnormal budding of the tracheobronchial analog of the primitive foregut. Most BCs develop in the pulmonary parenchyma or mediastinum in relation to the tracheobronchial system. However, cervical, cutaneous, gastric, esophageal, diaphragmatic, and intra-abdominal BCs are reported in literature. Exact mechanism of development of abdominal BCs is unclear, however, it is known that during early embryonic life, the thoracic and abdominal cavities communicate through paired pericardioperitoneal canals., Fusion of the caudal pleuroperitoneal membranes during formation of the diaphragm separates the pleural cavity from the peritoneal cavity. Sumiyoshi et al. postulated that subdiaphragmatic BCs result when abnormal buds of the tracheobronchial tree are pinched-off by the fusion of these membranes and migrate into the abdominal cavity through the pericardioperitoneal canal. In their review of all subdiaphragmatic BCs reported till 2001, Kim et al. reported 17 retroperitoneal and only nine intraperitoneal BCs. A comprehensive review of English language literature by Liang et al. in 2005 showed only 48 citations of subdiaphragmatic BCs, the majority of which were retroperitoneal and only a handful involved the lesser sac.
Histologically, BCs must have a ciliated epithelium (pseudostratified columnar or cuboidal) along with cartilage or bronchial mucous glands and muscle in the wall. Differential diagnosis of BC from teratoma is crucial as the behavior and management of both lesions are different., Roma et al. analyzed the pathologic features that can be used diagnostically to distinguish these two entities. They observed that BCs are usually cystic lesions, whereas the majority of teratomas contain solid areas. Further, histologically, BCs reflect exclusive differentiation toward the tracheobronchial tree, with respiratory type lining epithelium, organized smooth muscle bundles surrounding the epithelial lumina, and the presence of seromucinous glands in the wall. In contrast, teratomas undergo differentiation toward multiple tissue types and therefore, gastrointestinal, respiratory or squamous lining may all be seen. Immature cellular elements strongly favor teratoma. Smooth muscle and cartilage are also found in teratomas, however, these elements are arranged in a haphazard manner that have no resemblance to the tracheobronchial tree. The immunohistochemical profile of the two entities also reflects there differentiation. Roma et al. noted in their study that all BCs were positive for CK7 but negative or positive for CK20 only in rare cells and negative for chromogranin and Ki-67, similar to normal lung tissue. They also observed that while 18% of BCs were positive focally for TTF1, all cases were uniformly CDX2 negative in accordance with their differentiation from the tracheobronchial tree. In contrast, teratomas showed variable positivity for CK7, CK20, TTF1, CDX2, and chromogranin thus reflecting their multilineage, including enteric and respiratory, differentiation. If TTF-1 staining is performed, finding glands with dual staining for CDX-2 and TTF-1 is diagnostic of teratoma. However, it is important to note that most BCs can be reliably distinguished from teratoma on histology alone, and immunohistochemical analysis is rarely needed.
Intra-abdominal BCs are often asymptomatic and usually incidentally discovered on radiologic investigation. In symptomatic cases, symptoms are usually non-specific due to cyst expansion and compression of adjacent structures, rupture or hemorrhage, and secondary infection within the cyst. St. Georgeset al. suggested that all visible BCs should be completely resected because majority of them will eventually become symptomatic or complicated. A rarely seen but dangerous possibility of malignant transformation within the cyst wall also exists. Moersch and Clagget first reported two cases of adenocarcinoma and squamous cell carcinoma respectively in thoracic BCs in 1947. Kirmani et al. reviewed 683 adult patients with BC in 2010 and reported a malignancy incidence of 0.7% with malignancy developing in 5 patients. These included one squamous cell, one adenocarcinoma, two bronchioloalveolar, and one large-cell anaplastic carcinoma. Other reported malignancies include fibrosarcoma, undifferentiated carcinoma, leiomyosarcoma, embryonal rhabdomyosarcoma, and carcinoid tumor. Notably, almost all these cases pertain to thoracic BCs and till now only case of adenocarcinoma arising in an intra-abdominal (retroperitoneal) BC has been documented. To the best of our knowledge, no case of malignancy arising in a lesser sac BC has been reported in literature thus far. Because of paucity of cases, the pathogenesis of malignancy in BC remains unclear. Some workers have suggested that unstable epithelial cells in the cyst wall could have malignant potential and lead to malignancy. Further, it has been recognized that chronic inflammatory processes may stimulate neuroendocrine cell proliferation. Subepithelial chronic inflammation and fibrosis in the cyst wall seen in our case may be indicative of a similar pathogenic mechanism. Previously reported carcinoid tumors in thoracic BCs were also associated with cyst inflammation and fibrosis., Our case is even more unusual as it illustrates the concurrent presence of another cystic lesion (hydatid cyst) in the same patient. The combination of hydatid cyst with a foregut cyst has previously only been reported once by Schreurs in 1995. This concomitance could be, however, only a chance finding.
In conclusion, the present case illustrates that, although extremely rare, BCs must be considered in the differential diagnosis of lesser sac cystic lesions and possibility of neoplastic change within the cyst wall must be kept in mind. A policy of complete surgical resection and thorough pathologic examination will aid in the detection of possible malignant transformation, even in asymptomatic patients.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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