Pancreatic Lipomatous Hamartoma: A Hitherto Unrecognized Variant

Ductal hamartoma of the pancreas: A clinicopathologic study

BACKGROUND

Benign ductular proliferative lesions that resemble hepatic von-Meyenburg Complexes(VMC)/bile duct hamartomas have been noted to occur in the pancreas, but their incidence, clinicopathologic features and pathogenesis remains unknown. We present herein 3 patients that presented as cysts and call them pancreatic ductal hamartomas (PDH).

METHODS

Three cases of PDH were identified form a multi-institutional collaborative group, and their clinicopathological were reviewed. In addition, we also examined 115 consecutive pancreatic resections at our institutions for the presence of incidental PDHs.

RESULTS

The lesions were detected in each case during imaging for abdominal symptoms or grossing. The clinical suspicion was intra-ductal pancreatic mucinous cystic neoplasm (IPMN) in each case that led to pancreatectomy. The cyst fluid CEA was elevated in 2 of the patients tested. The patient age and gender were 73/M (case1), 68/F (case2) and 73/M (case3). In case1 besides the larger cystic lesion, numerous tiny lesions (0.1-0.3 cm) were seen throughout the pancreas. In case2 this was the only lesion, while in case3 there was another gastric-type IPMN with high-grade dysplasia. PDH were identified in 5(4.3%) of 115 consecutive pancreatectomy specimens. The PDHs measured 0.1-2.3 cm, and the histology is characterized by proliferation of irregular ductal structures lined by bland flattened to low columnar epithelium, variable cystic change and inspissated luminal secretions. The lining epithelium varied from non-mucinous pancreatico-biliary type to mucinous gastric foveolar-type, with occasional squamous metaplasia.

SUMMARY

PDH are seen in 4.5% of all pancreatectomy specimens and detected incidentally, but occasionally may become large and/or cystic enough leading to pancreatectomy. Their relationship to pancreatic carcinoma or IPMN remains currently unknown.

Imaging and histopathologic characteristics of typical pancreatic hamartoma: a case report and literature review

Background

Pancreatic hamartoma, a rare benign non-neoplastic condition, presents challenges in differentiating from other pancreatic diseases due to its atypical imaging and unreliable biopsy results. In this study, we present a case of pancreatic hamartoma and conduct a comprehensive review of relevant literature to outline its characteristic features, aiming to underscore its clinical relevance and implications.

Case presentation

A 63-year-old man presented with a pancreatic mass, discovered during evaluation of abdominal pain and distension. Laboratory tests were largely unremarkable. Ultrasound revealed a hypoechoic mass in the head of the pancreas. Subsequent computed tomography and magnetic resonance imaging demonstrated an inhomogeneous mass with a clear boundary in the uncinate process of the pancreas. Furthermore, a distinct delayed enhancement pattern was noted on imaging. Histopathological examination confirmed the diagnosis of pancreatic hamartoma.

Conclusions

Preoperative diagnosis of pancreatic hamartoma remains challenging. Imaging modalities can play a crucial role in facilitating accurate diagnosis and potentially avoiding unnecessary surgical intervention in patients with this condition.

Comments and illustrations of the European Federation of Societies for Ultrasound in Medicine guidelines: Rare pancreatic tumors, ultrasound and contrast-enhanced ultrasound features-Malignant mesenchymal tumors

Rare malignant mesenchymal pancreatic tumors are systematized and reported in this review. The focus is on the appearance on imaging. The present overview summarizes the data and shows that not every pancreatic tumor corresponds to the most common entities of ductal adenocarcinoma or neuroendocrine tumor.

Pancreatic hamartoma: detection of harbouring NAB2-STAT6 fusion gene

AIM

Hamartomas in the pancreas are rare and are often histologically and morphologically similar to solitary fibrous tumours (SFTs). We examined the differences between hamartomas and SFTs at the molecular level.

METHODS AND RESULTS

Thirteen patients histopathologically diagnosed with pancreatic hamartoma were included in the study. We also performed STAT6 immunohistochemistry (IHC), which is used in the diagnosis of SFT. Furthermore, for the three cases in which RNA was extracted, reverse transcription polymerase chain reaction to search for NAB2-STAT6 fusions was used. Macroscopically, 13 patients had well-demarcated tumour lesions. Histologically, no islets of Langerhans were observed in the lesions, acinar tissue and ducts were unevenly distributed, and elastic fibres were not observed around the ducts by Elastica Van Gieson staining. One case contained a lipomatous hamartoma composed mainly of adipose tissue. Seven of the 13 cases demonstrated expression of STAT6 in the nuclei of intervening spindle cells. NAB2-STAT6 fusions were observed in two of the three cases in which RNA was extracted. These two cases also demonstrated STAT6 expression in spindle cells using STAT6 IHC. In one case of lipomatous hamartoma, we did not confirm NAB2-STAT6 fusion or STAT6 expression in STAT6 IHC.

CONCLUSION

Of the 13 patients histopathologically diagnosed with hamartoma, two demonstrated NAB2-STAT6 fusions, suggesting the existence of pancreatic hamartomas with molecular-level components identical to those of SFT.

Rare case of pancreatic lipomatous hamartoma

A middle-aged man had an incidental finding of 10.1 cm lipomatous mass arising from pancreatic body/neck detected on CT scan. He was asymptomatic. He underwent surgical resection of the mass due to concern for malignancy. His postoperative course was complicated by a high-volume pancreatic leak of approximately 900 mL/day. He underwent endoscopic retrograde cholangiopancreatography and insertion of a pancreatic stent, with some improvement in the pancreatic leak. His leak eventually settled after 3 months. The final histopathology showed lobules of mature adipocytes with small islands of disorganised benign pancreatic ducts and acini interspersed within them, suggestive of pancreatic hamartoma of lipomatous variant. Pancreatic lipomatous hamartomas are rare and are often diagnosed on final histopathology when the initial resection was performed due to diagnostic uncertainty or concern for malignancy. It is a benign lesion with an indolent course and must be discriminated from other lipomatous lesions of the pancreas. An awareness of the condition is important to help guide management.

Pancreatic Hamartoma Difficult to Diagnose Preoperatively

Abdominal ultrasonography in a 70-year-old woman showed a hypoechoic mass, 14 mm in diameter, in the pancreatic body. Computed tomography showed a mass with contrast effect in the pancreatic body. Test results for endocrine factors or tumor markers were normal. The initial consideration was nonfunctional pancreatic neuroendocrine tumor. Over 8 years of monitoring, the tumor diameter increased to 18 mm, until pancreatic tumor enucleation was performed. The postoperative diagnosis was pancreatic hamartoma, a rare type of benign pancreatic tumor. The preoperative diagnosis of pancreatic hamartoma is difficult, but consideration must be given to the possibility of hamartoma when encountering pancreatic tumors.

A typical case of resected pancreatic hamartoma: a case report and literature review on imaging and pathology

Background

Pancreatic hamartomas are rare entities and difficult to diagnose before resection. We report a case of resected pancreatic hamartoma and literature review of typical characteristics of the lesion.

Case presentation

A 78-year-old man presented with a mass in his pancreas, which was incidentally identified when he experienced pneumonia. No remarkable symptoms were observed, and laboratory tests showed no abnormalities, except a slight carcinoembryonic antigen elevation. Enhanced computed tomography and magnetic resonance imaging showed a well-demarcated solid mass with heterogeneous contrast that was 2 cm in size. A gradual enhancement pattern was also observed. The biopsy revealed no specific findings; therefore, surgical resection was necessitated to confirm the diagnosis. Histopathologically, ducts, acinar cells, and adipose cells without atypia were observed among abundant fibrous stroma, but islets of Langerhans and peripheral nerves were absent. An immunohistochemical examination demonstrated CD34 and c-kit positive staining in the stromal cells, S-100 positivity in the adipose cells, and a lack of elastic fibers in the duct walls. The lesion was diagnosed as a pancreatic hamartoma.

Conclusion

Asymptomatic pancreatic hamartomas can avoid resection. A careful consideration of imaging and appropriate immunohistochemistry of biopsy specimen may facilitate accurate diagnosis before resection. Therefore, sufficient recognition of the characteristics of pancreatic hamartomas is desirable.

Imaging findings for pancreatic Hamartoma: two case reports and a review of the literature

BACKGROUND

Pancreatic hamartoma is an extremely rare benign disease, and previous reports have provided little detail regarding its appearance in imaging. As a result, we report the imaging findings for two cases of pancreatic hamartoma.

CASE PRESENTATION

One 57-year-old female patient and one 69-year-old male patient presented with pancreatic lesions incidentally detected by US; CT and MRI revealed a 2.9-cm cystic and solid lesion and a 1.4-cm solid lesion, respectively. US showed a hypoechoic well-defined mass in the pancreatic head. The plain CT indicated that the internal density was uneven, and the lesions showed obvious progressive enhancement. The MRI-T2WI showed iso- to high-intensity, the DWI showed iso-intensity, and the masses also all showed obvious progressive enhancement. Histopathological studies confirmed the diagnosis of pancreatic hamartoma.

CONCLUSION

Pancreatic hamartoma is an extremely rare tumour with benign features, such as no dilatation of the MPD and well-defined, slight hyperintensity or iso-intensity on T2WI and iso-intensity on DWI, with obvious progressive enhancement. Therefore, detailed review of multiple imaging modalities may help in diagnosis of PH and prevent unnecessary surgery for patients with this diagnosis.

Malformations, choristomas, and hamartomas of the gastrointestinal tract and pancreas

Congenital and hamartomatous lesions of the gastrointestinal tract cause diagnostic challenges for surgical pathologists. Many of these are merely histologic curiosities, whereas others have substantial clinical implications because they herald cancer syndromes or associated anomalies. Although a comprehensive discussion of all developmental abnormalities that can occur in the gastrointestinal tract is beyond the scope of a single manuscript, some entities are more likely to be encountered by surgical pathologists, have important clinical consequences, or pose diagnostic difficulties. The purpose of this review is to discuss the more common malformations and choristomas, as well as hamartomatous lesions that may be clinically important due to their risk for cancer development, frequent associations with heritable cancer syndromes and other anomalies, or potential to simulate other entities.