Clinical diagnosis
Case 187
【Progress】
He was planned to have needle biopsy under endoscopic ultrasound through gastric wall.
【Discussion】
Hamartoma is thought to be an error growth in the development process (1). Excessive growth or proliferation of cells or components of the original organ are found. The cells composed of hamartoma are the same as normal mature cells. It can occur in any part of the whole body. It can contain fibrin, adipose, gland, cartilage, bone and nerve depending on the origin. It is controversial to differentiate hamartoma from benign tumor or hyperplasia (1). It does not grow to be so harmful as to threaten the life of host. However, it might induce negative effect on the function of organ by compression of its large volume (2).
As typical examples, hamartoma of hypothalamus, basal ganglion, breast, lung, liver and bone are listed. It is important thar hamartoma in each part does not have the common histologic component but can differ in each origin. For an example, the histology findings of hamartoma originated from brain and breast are completely different. Tuber cinereum which is included in hypothalamus sometimes is a common place of hamartoma. Histologically it composes of accumulation of neuron and glia which are collectively disorganized. Enhanced MRI using Gd shows no remarkable enhancement, inducing the same intensity as the surrounding brain. Hamartoma associated with neurofibromatosis type I occurs in basal ganglion. Its pathological findings show glia cells, ganglion cells, abundant disoriented axon and thin wall vessels (3).
Breast hamartoma contains normal breast component: terminal ductal lobular unit, fat and hyalinized stroma. Mammography shows breast in a breast with circumscribed by hyaline tissue.
Lung hamartoma composes of matured but disorganized hyaline cartilage, smooth muscle, fat and respiratory epithelium. Typical radiological finding is a nodule situated with smooth margin and calcification in the peripheral area.
Liver mesenchymal hamartoma occurs in an infant less than 3 years and the most third hepatic tumor of the liver following hepatoblastoma and infantile hemangioma. Pathologically, it includes well circumscribed myxoid mass with fluid filled mass with disorganized bile duct. Biliary hamartoma composes of small biliary tracts (tractules) most sized less than 5mm. They are surrounded by thick connective tissue with no communication with normal bile duct.
Bone islands are thought to be a developmental error of resorption process by osteoclasts and/or osteoblasts, being classified as bone hamartoma by some pathologists (4).
Splenic hamartoma is histologically classified as red pulp type, white pulp type and fibrous type and radiologically classified into fibrous type and non-fibrous type. In hamartoma including dominant fibrous tissue, MRI showed hypo- or iso-intensity on T1WI and hypo-intensity on T2WI.
Pancreatic hamartoma is classified into cystic type and solid type (5-10). Cystic type composes of pancreatic duct while solid type composes of fibrous tissue and adipose tissue. Cystic hamartoma is reported to configurationally change into solid hamartoma as time progress (10). In our case, the lesion with well-demarcated contour in pancreas body includes solid components with adipose tissue on MRI with out-of-phase and in-phase, although it mimics a cystic lesion on CT. The solid mass including adipose tissue on pancreas is thought to be suspicious pancreatic hamartoma.
【Summary】
We present a sixty seven-year-old male for thickened calcified gall bladder and pancreatic cyst. Abdomen CT showed a 4cm-sized well-demarcated cyst-like lesion whose CT value – 5.4 (-35 to 25). MRI with out-of-phase and in-phase showed the lesion composed of solid including adipose. It is borne in mind that pancreas hamartoma is classified into two types; cystic and solid. Cystic hamartoma composes of mature pancreatic duct and solid hamartoma composes of alveolar cells, fibrous and adipose. Cystic hamartoma can change into solid hamartoma as time progress. Hamartoma is a developmental error and histologic findings differ dependent upon an emerging origin. We discuss hamartoma on histological and radiological findings arising from hypothalamus, basal ganglion, breast, lung, liver, bone, spleen and pancreas.
【References】
1.Nagata S, Yamaguchi K, Inoue T, Yamaguchi H, Ito T, Gibo J, et al. Solid pancreatic hamartoma. Pathol Int. 2007;57:276–280. doi: 10.1111/j.1440-1827.2007.02090.x.
2.Inoue H, Tameda M, Yamada R, Tano S, Kasturahara M, Hamada Y, et al. Pancreatic hamartoma: a rare cause of obstructive jaundice. Endoscopy. 2014;46:E157–E158. doi: 10.1055/s-0034-1364953
3.Brownlee RD, et al. Symptomatic hamartoma of the spinal cord associated with neurofibromatosis type 1. Case report. J Neurosurg. 1998 Jun;88(6):1099-103.
4.Greenspan A. Bone island (enostosis): current concept--a review. Skeletal Radiol. 1995 Feb;24(2):111-5
5.Izbicki JR, Knoefel WT, Müller-Höcker J, Mandelkow HK. Pancreatic hamartoma: a benign tumor of the pancreas. Am J Gastroenterol. 1994;89:1261–1262.
6.Wu SS, Vargas HI, French SW. Pancreatic hamartoma with Langerhans cell histiocytosis in a draining lymph node. Histopathology. 1998;33:485–487. doi: 10.1046/j.1365-2559.1998.0491c.x.
7.McFaul CD, Vitone LJ, Campbell F, Azadeh B, Hughes ML, Garvey CJ, et al. Pancreatic hamartoma. Pancreatology. 2004;4:533–538. doi: 10.1159/000080528.
8.Nagata S, Yamaguchi K, Inoue T, Yamaguchi H, Ito T, Gibo J, et al. Solid pancreatic hamartoma. Pathol Int. 2007;57:276–280. doi: 10.1111/j.1440-1827.2007.02090.x.
9.Kawakami F, Shimizu M, Yamaguchi H, Hara S, Matsumoto I, Ku Y, et al. Multiple solid pancreatic hamartomas: A case report and review of the literature. World J Gastrointest Oncol. 2012;4:202–206. doi: 10.4251/wjgo.v4.i9.202.
10.Matsushita D, et al. Pancreatic hamartoma: a case report and literature review. BMC Gastroenterol. 2016 Jan 14;16:3. doi: 10.1186/s12876-016-0419-2.
2020.4.8