Indian Journal of Pathology and Microbiology

CASE REPORT
Year
: 2020  |  Volume : 63  |  Issue : 3  |  Page : 456--459

Schwannoma: An uncommon dweller in the adrenal gland


Chaithra G Venkataramana1, Saraswathy Sreeram1, PV Santosh Rai2, GG Laxman Prabhu3, KN Sanman3, Shrinath P Shetty4,  
1 Department of Pathology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
2 Department of Radiodiagnosis, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
3 Department of Urology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India
4 Department of Endocrinology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka, India

Correspondence Address:
Saraswathy Sreeram
Department of Pathology, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education, Manipal, Karnataka
India

Abstract

An elderly adult woman presented with upper abdominal pain to the urology department. Imaging studies revealed a right adrenal lesion with central necrosis, abutting the large vessels and suggestive of malignancy. Histopathology showed an encapsulated spindle cell tumor with marked nuclear atypia, cystic change, and hemorrhage. S100 immunomarker was strongly and diffusely positive. Final diagnosis was ancient schwannoma with secondary change. Schwannomas are rare in the adrenal gland, with <50 cases reported in the literature. These incidentally detected nonfunctional adrenal tumors need confirmation with histopathology and ancillary studies.



How to cite this article:
Venkataramana CG, Sreeram S, Santosh Rai P V, Laxman Prabhu G G, Sanman K N, Shetty SP. Schwannoma: An uncommon dweller in the adrenal gland.Indian J Pathol Microbiol 2020;63:456-459


How to cite this URL:
Venkataramana CG, Sreeram S, Santosh Rai P V, Laxman Prabhu G G, Sanman K N, Shetty SP. Schwannoma: An uncommon dweller in the adrenal gland. Indian J Pathol Microbiol [serial online] 2020 [cited 2020 Oct 25 ];63:456-459
Available from: https://www.ijpmonline.org/text.asp?2020/63/3/456/291663


Full Text



 Introduction



Schwannomas are benign tumors arising from neoplastic Schwann cells, which surround the peripheral nervous system.[1] Their usual location is in the cerebellopontine angle or in the spinal nerve roots in extremities.[2] Only 0.7% of schwannomas show a retroperitoneal location.[3] The case described here is of an adrenal mass detected on imaging and confirmed as schwannoma by histopathology. Conventional schwannomas have a characteristic histology; however, variants like cellular and ancient schwannomas need to be confirmed by ancillary studies like immunohistochemistry.[4] Only about 40 cases of adrenal schwannoma have been described in the literature, and hence, the significance of this case report.[5]

 Case History



A 55-year-old woman presented with vomiting since a week, mild right upper abdominal pain of 10 days duration, and loose stools. She was a diabetic and hypertensive. There was no history of any tumor in the family members. On examination, her blood pressure was 170/100 mmHg. Ultrasound showed a right adrenal mass–like lesion of size 6 × 4.9 cm. Computed tomography revealed a heterogeneous lesion arising from the lateral limb of right adrenal gland, measuring 5.3 × 5.4 × 5.5 cm with central necrosis [Figure 1]. Arterial and venous enhancement with evidence of washout in delayed phases was noted. There was no evidence of calcification. The lesion was compressing the right renal vein and inferior vena cava (IVC) junction. Radiological differential diagnosis was of a pheochromocytoma (PCC) or adrenal carcinoma. Electrolytes, free metanephrine (0.67 pg/mL), and nor-metanephrine levels (71.8 pg/mL) were normal in serum, indicating a nonfunctional tumor.{Figure 1}

Right open adrenalectomy was done with an incision in the right flank from the lateral margin of the rectus along the bed of the 11th rib. Suprarenal mass of 6 × 5 cm was seen abutting IVC, right renal vein, and duodenum [Figure 2]a. A suspicion of adrenal cortical carcinoma was raised intraoperatively. The surgical specimen measured 6.5 × 6 × 4 cm and showed compressed normal adrenal of size 3.5 × 5 × 0.5 cm at the periphery. A well-demarcated, solid, and focally cystic tumor was seen with myxoid cut surface and focal hemorrhage [Figure 2]b.{Figure 2}

Histological sections showed cellular tumor composed of spindle cells with indistinct borders arranged in bundles, interlacing fascicles, and vague palisading patterns [Figure 2]c. The nuclei were elongated and twisted, with areas showing bizarreness, hyperchromasia, multilobation, and marked atypia [Figure 2]d and [Figure 2]e. Accumulation of siderophages [Figure 2]f, foamy histiocytes, lymphocytes, and plasma cells was seen. Cystic change, hemorrhage, and xanthomatous change [Figure 2]g were also noticed. Hyalinized blood vessels and lymphocytic cuffing were noticed in a peritumoral location [Figure 2]h. Necrosis and mitosis were absent. Verocay bodies were not seen. Histological diagnosis was schwannoma with ancient change.

An immunohistochemical panel was used for confirmation. S100 showed diffuse and strong positivity [Figure 3]a and [Figure 3]b. SMA [Figure 3]c, synaptophysin, and neuron-specific enolase [Figure 3]d were negative. Calretinin showed weak and focal positivity [Figure 3]e. Final diagnosis was given as adrenal schwannoma with secondary change.{Figure 3}

The patient was discharged on the sixth postoperative day with follow-up on suture removal after 10 days. She has been asymptomatic till date and scans are normal after 10 months of surgery.

 Discussion



Schwannomas are seen in persons of age 20–50 years with a slight predominance in women. They form only <0.2% of adrenal masses. They are well-encapsulated and hypervascular tumors derived from neural crest cells usually seen in adrenal medulla.[3] The medulla is innervated by phrenic and vagus nerves as well as the sympathetic trunk.[5] Schwannomas are associated with neurofibromatosis, von Recklinghausen's disease and prior ionizing radiation.[2]

These tumors are usually detected by chance. The patient in this report had abdominal pain probably because of the compression effect as the tumor was >5 cm in size. The heterogeneous appearance on imaging was due to the secondary cystic change, degeneration, and hemorrhage. Magnetic resonance imaging findings would typically be a heterogeneous mass appearing hypointense on T1-weighted imaging and heterogeneously hyperintense on T2-weighted imaging showing heterogeneous Gadolinium contrast enhancement with cystic/necrotic areas appearing as T2 hyperintense nonenhancing areas. Calcified areas would appear as hypointense foci on both T1- and T2-weighted imaging.[6] PCCs cannot be distinguished from schwannoma on imaging as both show heterogeneous enhancement.[7]

Schwannomas do not usually produce any hormones and, hence, are nonfunctional. However, urinary catecholamines were raised in one case report of adrenal schwannoma.[8] In our case, metanephrine levels were normal.

The characteristic microscopic appearance of conventional schwannomas is of alternating hypercellular Antoni A and hypocellular Antoni B areas.[2] Ackerman and Taylor were the first to describe ancient change in schwannomas.[3] Cystic change, hemorrhage, and calcification are common and, hence, show a heterogeneous appearance on imaging.[7] They have a characteristic hyalinized matrix, signifying a long-standing and slow-growing process.[3] Strong and diffuse S100 immunoreactivity is, many a times, the cornerstone of diagnosis.[2]

The differential diagnoses on microscopy are PCC, ganglioneuroma, leiomyoma, solitary fibrous tumor (SFT), gastrointestinal stromal tumor (GIST), melanoma, neurofibroma (NF), and sustentaculoma.[5] Malignant peripheral nerve sheath tumors were excluded in this case, in spite of marked nuclear atypia, because of the lack of necrosis and mitoses.[2]

Spindled variant of PCC shows a nested pattern with immunopositivity for synaptophysin and chromogranin and S100 negativity. Extensive sampling is needed to rule out ganglioneuroma to look for ganglion cells as the spindled areas in this tumor can sometimes predominate.[5] Leiomyomas have blunt nuclei in contrast to the tapering nuclei in schwannoma. Also, fibrillary cytoplasm, SMA, and desmin positivity help distinguish them from schwannomas. SFTs show bland spindle cells arranged in a patternless pattern with a characteristic immunophenotype of CD34+ and S100−.[9] GISTs show CD117 and DOG1 positivity. Melanomas demonstrate characteristic prominent eosinophilic nucleoli with positivity for HMB45, S100, and Melan A.[5],[9]

Out of all the differentials mentioned above, probably the most challenging ones to differentiate from schwannoma are NF and sustentaculoma.[5] Sustentaculomas of adrenal glands are relatively recently described.[10] NFs are also known to show secondary changes.[9] All these tumors are S100+.[5],[9],[10] Electron microscopy seems to be the distinguishing modality between schwannomas, NF, and sustentaculomas. NFs show a mixture of cells, whereas schwannomas comprise only of Schwann cells.[8] Sustentaculomas show cytological blandness and inflammation like schwannomas.[10] Schwannomas show a characteristic well-defined basal lamina on electron microscopy, whereas sustentaculomas lack it.[5],[10]

Adrenocortical carcinomas show positivity on immunostaining for vimentin, synaptophysin, Melan-A, calretinin, and inhibin, and this is important for separating adrenal cortical neoplasms from PCCs and other tumors.[11]

Surgical excision is the curative management in these cases as the biologic potential of these tumors is difficult to be judged on imaging alone.[7] Surgery is indicated in adrenal tumors of size more than 4 cm, with radiological suspicion of malignancy and laboratory evidence of functionality.[3]

Schwannomas with secondary change need to be considered as differentials in cystic masses of retroperitoneum. Imaging with histopathology and correlation with ancillary studies might be needed for conclusive diagnosis. There have only been <50 cases of schwannomas reported in the adrenal glands.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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