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Sarangi S, Nalwa A, Varshney VK, Yadav T, Vishwajeet V, Bharti JN. Mucinous cystic neoplasm of liver masquerading as Hydatid cyst: Important lesson learned. Indian J Pathol Microbiol 2022;65:482-4
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Sarangi S, Nalwa A, Varshney VK, Yadav T, Vishwajeet V, Bharti JN. Mucinous cystic neoplasm of liver masquerading as Hydatid cyst: Important lesson learned. Indian J Pathol Microbiol [serial online] 2022 [cited 2022 May 5];65:482-4. Available from: https://www.ijpmonline.org/text.asp?2022/65/2/482/343160
Mucinous cystic neoplasms of liver (MCN-L) are rare neoplasms comprising less than 5% of cystic lesions of liver., They occur exclusively in females with mean age being 51 years. Recent WHO classification recommended that the term MCN L should be reserved for cysts with presence of an underlying ovarian stroma only., We, hereby, present two cases, clinically and radiologically diagnosed as hydatid cyst and proven as MCN-L on histopathology.
1: A 32-year-female presented with dull aching and non-radiating pain in upper abdomen for 1 month, associated with epigastric fullness. On USG abdomen, there was presence of large multi-loculated cystic lesion in right lobe of liver and on contrast enhanced computerized tomography (CECT), a well-defined cystic lesion with smooth wall and thin septae in segment III and IV of liver (10 × 10 cm) was seen, suggestive of hydatid cyst (HC). After robotic deroofing, gross examination revealed multiple flattened tissue pieces altogether measuring 5.2 × 5.4 × 5 cm. Microscopic examination revealed a multiloculated cyst lined by columnar epithelium having abundant intracytoplasmic mucin with underlying ovarian type stroma arranged in storiform and short fascicular pattern with strong nuclear expression of Estrogen Receptor alpha (ER) [Figure 1]a and [Figure 1]b. In addition, few small interspersed cohesive clusters of epithelial cells were seen, positive for alpha inhibin and a diagnosis of MCN-L was rendered [Figure 1]c.
|Figure 1: Cyst lined by low columnar epithelium with basally located nuclei and apical mucin with underlying ovarian-type stroma (a, Haematoxylin and Eosin 400x) showing diffuse nuclear immunopositivity for ER alpha and inhibin (b and c respectively, IHC 400x)|
2: A 57-year-female presented with dull aching pain in right upper abdomen since 6 months with a lump in right hypochondrium since 1 month, gradually progressive in size. Ultrasound followed by MRI abdomen was suggestive of a large cystic lesion (~13.6 × 12.4 cm) in segment IVB of liver, provisionally diagnosed as HC. Histopathology was suggestive of MCN-L with no features of high-grade dysplasia or malignancy with ovarian type stroma underneath epithelium. Patient was eventually lost to follow up. After 2 years she returned with complaints of pain in upper abdomen of 1-month duration. MRI abdomen showed persistent multilocuated cystic lesion in remaining segment IVB of liver measuring ~6.4 × 4.9 × 6.1 cm [Figure 2]a and [Figure 2]b. Multiple enhancing internal septations were identified with maximum thickness of 2 mm. Resection of segment IVB and V with gall bladder was performed.
|Figure 2: Magnetic resonance imaging of liver – Axial T1 (a), T2 (b) weighted images show a T1 hypointense, T2 hyperintense unilocular cystic mass lesion (white arrows) involving segment IV, V of liver with clear fluid contents. Cyst is causing biliary compression with resultant bi-lobar intrahepatic biliary radical dilatation (black arrows)|
On gross examination, a cystic mass was identified measuring 7.5 × 6 × 3 cm and weighing approximately 66.4 gm, surrounded by liver parenchyma on all sides. On cut section, one multiloculated cyst was identified. On serial slicing cyst was partially solid and filled with greenish mucinous material.
On microscopic examination, a cyst lined by single layer of bland, cuboidal to low columnar focally ciliated epithelium was identified [Figure 3]. Epithelium showed focal areas of ulceration with underlying stroma displaying extensive xanthogranulomatous reaction composed of sheets of histiocytes, foreign body type of giant cells and cholesterol clefts, possibly as a reaction to previous biopsy of the lesion. Stroma was composed of densely packed spindled cells, histologically mimicking ovarian-type stroma.
|Figure 3: (a) Low power view shows a cyst with underlying stroma (Haematoxylin and Eosin 100x). (b) High power view shows columnar epithelium with ovarian type stroma underneath (Haematoxylin and Eosin 400x). (c and d) The stromal cells show diffuse nuclear positivity with ER and the lining epithelial cells are immunopositive for CK8/CK18 respectively (IHC, 400x)|
Mucinous cystic neoplasm of liver is an uncommon cystic neoplasm with reported incidence of 1 case per 20,000 to 100,000 person-years. It is frequently misdiagnosed in pre-operative setting due to its rarity and similar clinical presentations to other cystic liver lesions. This may lead to inappropriate treatment, such as aspiration, deroofing, partial excision etc., causing unnecessary morbidity. Hence, it needs to be diagnosed with precision by the clinicians, radiologists, and pathologists to ensure an accurate management of the patient.
The presenting symptoms are non-specific with patient presenting with a pain in upper abdomen, abdominal fullness, or awareness of lump. Pre-operative radiological diagnosis remains a challenge as inaccurate diagnosis may lead to incomplete excision. Radiologically, they have to be differentiated from IPMN-B, simple hepatic cysts, and HC.
Histopathological examination is necessary to classify these lesions, determine presence or absence of invasion and prognosis. Morphologically, non-invasive MCNs are filled with viscous, mucinous material and are lined by cuboidal to low columnar epithelium with basal nuclei and apical mucin. The lining epithelium may display features of low, intermediate, or high-grade dysplasia. The subepithelium is typically spindled and compact giving an appearance of ovarian stroma.
According to literature, ovarian stroma underlying the epithelium is embryonic in origin and is hypothesized to be the result of migration of gonadal cells to liver surface during development and it must prove itself by being immunoreactive to nuclear hormonal receptors ER alpha, Progesterone Receptor, and alpha inhibin. The lining epithelium is immunopositive for CK8/18, CK7 and CK19. Both cases shared identical morphology as well as immunoprofile.
Intraductal papillary neoplasm in bile ducts (IPMN-Bs) are considered major differentials of MCN-Ls, not to discount the importance of others like simple hepatic cysts, liver abscess, HC, congenital cystic dilatation, degenerated metastatic tumors, mucin producing metastatic tumors, cystic hemangioma, lymphangioma, hepatic foregut cyst, mesenchymal hamartoma and teratoma. The cyst-in-cyst appearance and presence of an ovarian-type stroma on biopsy of MCN-Ls puts the debate to rest.,
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Department of Pathology and Laboratory medicine, 1st floor, College building, All India Institute of Medical Sciences, Jodhpur, Basni Phase II, Jodhpur-342005, Rajasthsn
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