|Year : 2015 | Volume
| Issue : 1 | Page : 59-61
Lipomatous retroperitoneal ganglioneuroma
Rama Srivastava1, Smriti Agnihotri2, Nandyala Hari Sarma3
1 Department of Pathology, Sir Seewoosagur Ramgoolam Medical College, Mauritius
2 Department of Pathology, Sir Seewoosagur Ramgoolam Medical College, Mauritius, India
3 Department of Pathology, RDT Hospital, Andhra Pradesh, India
|Date of Web Publication||8-Dec-2014|
7, Bonnefin Frederic Street, Forest Side, Curepipe
Source of Support: None, Conflict of Interest: None
Fatty replacement of non-lipomatous tumors is rare. We report a case of retroperitoneal ganglioneuroma, showing fatty replacement in a 17-year-old adolescent male. The patient presented with a left lumbar mass. Ultrasound and computed tomography (CT) examination showed a 5 × 6 cm mass near the left adrenal gland. A diagnosis of myelolipoma was made clinically due to the proximity of the tumor to the adrenal gland and fat content of the tumor. Microscopic examination of the growth revealed extensive foci of fat scattered between the ganglioneuroma component. Fatty replacement of the ganglioneuroma has been documented only in four cases so far. A short review of the differential diagnosis of fat containing retroperitoneal masses is made along with emphasis on the pathological and clinical implications of lipomatous change.
Keywords: Ganglioneuroma, fatty replacement, retroperitoneal, retroperitoneal mass
|How to cite this article:|
Srivastava R, Agnihotri S, Sarma NH. Lipomatous retroperitoneal ganglioneuroma. Muller J Med Sci Res 2015;6:59-61
| Introduction|| |
Ganglioneuromas are fully differentiated tumors that contain no immature elements. They are rare when compared with other benign neural tumors, such as, schwannoma and neurofibroma. They are usually seen in children above 10 years of age and are most often located in the posterior mediastinum, followed by the retroperitoneum.  Microscopically ganglioneuroma resemble neurofibroma, with a dominant Schwannian stroma, along with the presence of fully mature ganglion cells. Fatty replacement of the ganglioneuroma is very rare. Only one case of lipomatous retroperitoneal ganglioneuroma  and three cases of mediastinal ganglioneuroma with fatty replacement are reported in the literature. ,, The presence of fat alters the tissue composition, hence, it alters their density when examined radiologically by imaging techniques like CT/magnetic resonance imaging (MRI), and serves as a useful diagnostic sign.  Histopathology still remains the gold standard in their diagnosis. This rare change also helps to narrow down the list of clinical differential diagnosis for retroperitoneal masses.
| Case Report|| |
A 17-year-old adolescent male came to the hospital with complaints of swelling in the back (lumbar region) and recurrent diarrhea. Physical examination did not reveal any significant findings, but for the swelling in the left lumbar region, which measured 5 × 6 cm. The past history and family history did not reveal any significant findings.
Routine laboratory investigations were within normal limits. An abdominal ultrasound showed a hypoechoic, hypovascular, left retroperitoneal paraspinal mass measuring 4.5 × 6 × 8 cm. Clinically, in this case, a list of retroperitoneal lesions were considered in the differential diagnosis - including Schwannoma, neurofibroma, ganglioneuroblastoma, neuroblastoma, malignant peripheral nerve sheath tumor, lymphoma, primitive neuroectodermal tumor, paraganglioma, hemangioma, fibroma, fibrosarcoma, lipoma, liposarcoma, chordoma, desmoid tumor, and teratoma.
An unenhanced CT showed a left paraspinal mass, which contained mixed attenuation including fat and soft tissue elements. Contrast-enhanced CT showed a predominantly enhanced density for the soft tissue components, while the signal intensity of the area of fat was reduced. Based on the radiological features, the long list of clinical differential diagnosis narrowed for schwannoma, ganglioneuroma, and an angiolipoma.
The patient was operated and the mass was removed. The specimen received was a well-circumscribed mass measuring 4 × 6 × 8 cm. The cut surface showed homogenous grayish-white areas mixed with small yellowish areas. A microscopic examination of the growth showed a well-circumscribed tumor composed of Schwannian cells, nerve fibers, and mature ganglion cells, with single or multiple nuclei. There were focal areas of calcification. Large amounts of adipose tissue were seen scattered between the tumor cell clusters [Figure 1], [Figure 2] and [Figure 3].
|Figure 1: Section shows tumor consisting of Schwann cells, ganglion, and lobules of adipocytes. H and E 10 ×|
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|Figure 2: Section shows a cluster of ganglion cells with prominent nucleus and eosinophilic cytoplasm, along with lobules of adipocytes and a cluster of Schwann cells. H and E 45×|
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|Figure 3: Section shows adipocytes, Schwann cells, and focal calcifi c areas. H and E 45×|
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On the basis of these findings a diagnosis of ganglioneuroma with focal fatty replacement was made.
| Discussion|| |
Ganglioneuromas show complete differentiation with no immature elements. The most common location for a ganglioneuroma is the mediastinum followed by the retroperitoneum. Only a minor proportion occur in the adrenal proper. 
Fatty replacement of ganglioneuroma is a rare finding. Pathologically, a fat component is seen commonly in a schwannoma, but rarely in a ganglioneuroma. , Histogenetically, it is considered as a metaplastic change. 
Most of the cases with fatty replacement were diagnosed radiologically; however, later they were confirmed histologically, as depicted in [Table 1].
|Table 1: Published cases of ganglioneuroma at different locations with fatty replacement|
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Ganglioneuroma is a tumor of the sympathetic nerve fibers arising from the neural crest cells. It belongs to neuroblastic tumor group, which includes ganglioneuroma, ganlioneuroblastoma, and neuroblastoma.  In this spectrum, the ganglioneuromas are benign, whereas, neuroblastomas are aggressive in nature and ganglioneuroblastomas are intermediate in biological behavior. Usually, patients with this condition are older than 10 years of age, compared to the neuroblastoma, which occurs in patients younger than three years of age.
Grossly, a ganglioneuroma is a well-circumscribed tumor with a fibrous capsule. On a cut section, it is gray to yellow with a homogenous surface. Thorough sampling for microscopic examination is crucial. Friable or hemorrhagic areas are particularly suspicious for having less differentiated elements. Fatty replacement of stroma is less readily picked up on gross examination, however, on radiographic examination, the fat replacement is easier to pick up and about one-third of the lesions are seen to have intralesional calcification. 
Histologically, the overall appearance of the ganglioneuroma resembles that of a neurofibroma. Scattered throughout, the Schwannian background are relatively mature ganglion cells. Typically their voluminous cytoplasm is bright pink and contains one to three nuclei.
For histopathological differential diagnosis, other retroperitoneal lesions containing fat include: Lipoma, neurolipoma, liposarcoma, myelolipoma, schwannoma, benign lipoblastoma, and lipoblastomatosis, diffuse lipomatosis, and teratoma.  Non-neoplastic lesions, with adipose tissue elements include fatty transformation of extramedullary hematopoiesis and panniculitis. 
Lipoma is rare during the first two decades of life Ϳ most become apparent in patients 40-60 years of age. Liposarcomas rarely occur in children. Liposarcoma-like lesions in this age group are apt to represent lipoblastoma, a fetal form of lipoma. Their peak incidence is in the sixth and seventh decades of life.
Myelolipoma, a tumor-like growth of mature fat and bone marrow elements is common in the retroperitoneum, but rare in young patients. They are usually seen in patients older than 40 years.  Lipoblastoma and lipoblastomatosis occur exclusively during infancy and early childhood. Microscopically there are lobules of lipoblasts in different stages of development. Diffuse lipomatosis is a rare diffuse overgrowth of mature adipose tissue that may occur in the abdominal cavity and pelvis. Most of these cases have an onset during the first two years of life, but are also seen in adolescents and adults. The presence of mature ganglion cells excludes all the above lipomatous tumors.
Neural fibrolipoma or neurolipomatosis manifests as a soft, slowly growing mass, consisting of proliferating fibrofatty tissue surrounding and infiltrating major nerves and their branches. However, these tumors principally involve volar aspects of the hands, wrists, and forearms of young persons.  The diffuse infiltration in these cases causes atrophy rather than proliferation of the neural elements. Again the presence of mature ganglion cells and Schwann cells delineates the above tumors from ganglioneuroma.
A retroperitoneal teratoma may be seen in children, showing mature neural and adipose tissue elements,  Teratomas are excluded when there is an absence of other elements from the ectoderm or mesoderm, apart from Schwann cells, ganglion cells, and fat.
| Conclusion|| |
The presence of Schwannian stroma with mature ganglion cells in the entire tumor area formed the basis for the diagnosis of ganglioneuroma in our case. Although ganglioneuromas are not rare, the significant fatty replacement of the tumor stroma is a rare finding and this change serves as a useful radiological and pathological tool to narrow down the list of clinical differential diagnosis for the retroperitoneal masses.
Finally, ganglioneuroma with fatty replacement, although a rare phenomena, should be included in the differential diagnosis of retroperitoneal fat-containing tumors. Further studies are required to see the prognostic significance of the presence of fatty replacement in the tumors.
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[Figure 1], [Figure 2], [Figure 3]