|Year : 2015 | Volume
| Issue : 3 | Page : 646
Extensive osteolytic skull base amyloidoma simulating malignancy: A rare pseudotumor producing a diagnostic dilemma
Meetu Agrawal1, Vineeta V Batra1, Kaushik Majumdar1, Lalendra Upreti2, Daljit Singh3
1 Department of Pathology, Govind Ballabh Pant Hospital, New Delhi, India
2 Department of Radiodiagnosis, Govind Ballabh Pant Hospital, New Delhi, India
3 Department of Neurosurgery, Govind Ballabh Pant Hospital, New Delhi, India
|Date of Web Publication||9-Oct-2015|
Vineeta V Batra
Department of Pathology, Academic Block, Govind Ballabh Pant Hospital, Jawaharlal Nehru Marg, New Delhi - 110002
Source of Support: None, Conflict of Interest: None
Although amyloidomas are quite well-known, intracranial, and especially skull base lesions have been rarely reported. Extensive lesions in the skull base frequently simulate malignancy clinicoradiologically. Diagnosis of these lesions is important as they offer a favorable prognosis. We describe a large infiltrating osteolytic skull base tumor-like lesion in a 45-year-old male without evidence of associated plasma cell dyscrasia. Squash smears and histopathology revealed a plasma cell-rich lesion with abundant amyloid, confirming amyloidoma. To conclude, amyloidoma of the skull base is a rare tumor-like lesion, with timely diagnosis and management offering a good prognosis.
Keywords: Amyloidoma, intracranial, malignancy, plasma cell dyscrasia, skull base
|How to cite this article:|
Agrawal M, Batra VV, Majumdar K, Upreti L, Singh D. Extensive osteolytic skull base amyloidoma simulating malignancy: A rare pseudotumor producing a diagnostic dilemma. J Can Res Ther 2015;11:646
|How to cite this URL:|
Agrawal M, Batra VV, Majumdar K, Upreti L, Singh D. Extensive osteolytic skull base amyloidoma simulating malignancy: A rare pseudotumor producing a diagnostic dilemma. J Can Res Ther [serial online] 2015 [cited 2020 May 31];11:646. Available from: http://www.cancerjournal.net/text.asp?2015/11/3/646/137999
| > Introduction|| |
Amyloidomas are described as localized deposits of amyloid leading to the formation of mass lesions, which form a rare presentation of amyloid related pathological abnormalities. These lesions may cause involvement and destruction of surrounding tissues and thus simulate locally aggressive tumors.
The skeleton itself and especially the skull base is a rare site of involvement for amyloidomas with only seven cases being reported till date to the best of our knowledge. ,,,,,, We present a case of skull base amyloidoma along with a comprehensive review of earlier reported cases.
| > Case report|| |
A 45-year-old male presented with gradually increasing proptosis of the right eye for last 4 years, accompanied by off and on headache. No associated neurological symptoms or sensorineural deficit were present. The general and systemic examinations were unremarkable.
Computed tomography (CT) scan revealed a large, ill-defined mass lesion involving the base of the skull, with erosions of the right temporal and sphenoid bones and multiple foci of coarse calcification [Figure 1]a. On magnetic resonance imaging (MRI), the infiltrative mass lesion involved the right temporal bone and appeared iso- to hyperintense on T1-weighted images and predominantly hypointense on T2-weighted images. Heterogeneous enhancement was seen on post-contrast images. The tumor extended into the infratemporal, anterior, and middle cranial fossa and also the extraconal space of right orbit [Figure 1]a. The surrounding brain parenchyma was unremarkable. Radiological differential diagnoses included a chondrosarcoma, intradiploeic meningioma, or an osteogenic sarcoma. There was no evidence of any other mass lesion elsewhere in the body.
|Figure 1: (a) Contrast-enhanced computed tomography (CT) scan showing a large heterogeneously enhancing mass lesion involving the right temporal and sphenoid bone; multiple foci of calcification are seen within the lesion (arrow); (b) photomicrograph of squash smear showing abundant background amorphous extracellular hyaline-like amyloid (arrow) along with a cellular population of mature and reactive plasma cells (H and E, ×200); (c) Photomicrograph showing nodular masses of amyloid in a background of reactive cell population (H and E, ×200). (d) Many foreign body giant cells were also seen (H and E, ×400)|
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Gross total resection of the soft tissue and adjacent involved bone was carried out through right subtemporal approach. The tumor was yellowish, soft, moderately vascular with well-defined margins at most of the places, but was found to erode the right temporal bone. Intraoperative squash smear cytology revealed cellular smears with mature plasma cells, foreign body giant cells, along with abundant extracellular amorphous, hyaline to eosinophilic material in the background [Figure 1]b.
Histopathological examination of the multiple fragmented tissue pieces received showed mature reactive plasma cells, histiocytes, lymphocytes, and foreign body giant cells [Figure 1] c-d. In addition, large masses of amorphous extracellular eosinophilic material, organized into rounded masses with concentric layering at places were observed [Figure 2] a and b. The material was pale pink on periodic acid-Schiff (PAS) and positive on Congo red stain with apple green birefringence on polarized light, confirming amyloid [Figure 2] c-d. Amyloid with collections of reactive plasma cells was also seen to infiltrate the intertrabecular spaces of bone included in the specimen. Immunohistochemistry (IHC) for kappa (ê) and lambda (ë) light chains revealed immune reactivity for both, indicating polyclonal population of plasma cells. A diagnosis of an extensive, infiltrative (osteolytic) skull base amyloidoma was rendered.
Further workup including bone marrow evaluation, serum, and urinary protein electrophoresis did not reveal any evidence of plasma cell dyscrasia. Abdominal fat pad aspirate was negative for amyloid. There was no history of bone pain or evidence of anemia, hyper calcemia, or renal failure. The patient is asymptomatic after 20 months of follow-up with no evidence of any recurrence or disease progression. The proptosis has reduced, but did not regress completely.
|Figure 2: (a) Nodular masses of amyloid with a concentric lamellatedappearance on periodic acid-Schiff and (b) H and E stains, respectively (×400. (c) The deposits are congophilic (Congo red, ×200) and (d) corresponding area showed apple green birefringence on polarized light (×200)|
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| > Discussion|| |
Formation of amyloid mass lesion (amyloidoma) is a rare presentation of amyloid-related pathological abnormalities and can affect any tissue.  The skeleton itself and specifically the skull base is a rare site of involvement. To the best of our literature search, only seven cases of skull base amyloidomas have been reported. ,,,,,, In this report, we have comprehensively reviewed all these cases [Table 1].
|Table 1: Comparative overview of the intracranial/skull base amyloidomas described in literature|
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Most cases of skull base amyloidomas were seen in males with an average age of diagnosis at 56.2 years. Despite the extent of involvement, all the lesions were indolent with a benign clinical course. The symptoms were related to the individual sites, for example, plugged ear, difficult mastication, proptosis (present case), neural compression, or local pressure effects [Table 1].
Radiologically, skull base and intracranial amyloid deposits commonly present as locally aggressive lesions causing destruction of the surrounding tissues, thereby leading to the erroneous radiological diagnosis of malignant tumors. , The tumor in this case extensively involved the infratemporal fossa and the orbit. However, brain invasion was not seen in any of these skull base amyloidomas including the present case. At the skull base, amyloidoma is an important radiological mimicker of chondrosarcoma, as it is locally destructive in flat bones, often with intralesional specks of calcification.
A preoperative confirmation of amyloidoma by fine needle aspiration (FNA) is usually not possible unless the lesion is at an accessible site. This underscores the importance of recognizing amyloid on intraoperative squash smears, as in the present case. The presence of plasma cells in a setting of bone erosive or osteolyticlesion may result in an erroneous diagnosis of multiple myeloma. In addition to adjunctive workup for plasma cell dyscrasia, care must be taken to identify the plasma cells as mature and reactive to prevent this diagnostic fallacy. Absence of monoclonal light chains (kappa or lambda) will also help in this regard. In addition, multinucleated foreign body giant cells (as a reaction to the amyloid) along with inflammatory infiltrate and calcific specks seen in this case may also lead tothe erroneous diagnosis of an osteolytic inflammatory lesion.
Serum and urinary protein electrophoresis are the common preliminary investigations that may be done for an etiological workup in tissue amyloidoma. Often associations may be found with plasma cell dyscrasias; treatment protocols are better defined for these cases. However, solitary amyloidoma occurring outside the setting of multiple myeloma is rare with around 37 cases reported in English literature.  Serology here may not be contributory and treatment depends on the extent of involvement.
To conclude, amyloidomas extensively infiltrating the skull base are extremely rare and deserve documentation. These lesions simulate malignancy on imaging and intraoperative appearance. Radiological awareness combined with intraoperative squash cytology and subsequent histology help to confirm the benign nature and guide further management.
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[Figure 1], [Figure 2]