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  Table of Contents    
CASE REPORT  
Year : 2015  |  Volume : 58  |  Issue : 3  |  Page : 368-370
Psammomatous melanotic schwannoma as a component of Carney complex


1 Department of Histopathology, SRM Institute for Medical Sciences, Chennai, Tamil Nadu, India
2 Department of Neurosciences, SRM Institute for Medical Sciences, Chennai, Tamil Nadu, India

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Date of Web Publication14-Aug-2015
 

   Abstract 

Melanotic schwannoma is a rare form of pigmented neural tumor commonly arising from the posterior spinal nerves and ganglia. Two variants have been described, psammomatous and nonpsammomatous. 50% of psammomatous tumors are associated with Carney complex. The biologic behavior of the tumor is difficult to predict and slightly over 10% of the tumors follow malignant course. We present a case of psammomatous melanotic schwannoma as part of Carney complex in a 67-year-old male. Clinical examination revealed oral mucosal and abdominal skin pigmentation. Magnetic resonance imaging showed an intradural extramedullary lesion at D8-D12 level. Intraoperative squash smear study showed sheets of spindle cells with abundant intracytoplasmic melanin pigmentation and few psammoma bodies. Based on clinical, radiologic, and histopathological findings with immunohistochemistry correlation a final diagnosis of psammomatous melanotic schwannoma was rendered.

Keywords: Carney complex, melanotic schwannoma, psammoma bodies

How to cite this article:
Shanmugam S, Ghosh M, Niamathullah S, Ghosh S. Psammomatous melanotic schwannoma as a component of Carney complex. Indian J Pathol Microbiol 2015;58:368-70

How to cite this URL:
Shanmugam S, Ghosh M, Niamathullah S, Ghosh S. Psammomatous melanotic schwannoma as a component of Carney complex. Indian J Pathol Microbiol [serial online] 2015 [cited 2022 Sep 25];58:368-70. Available from: https://www.ijpmonline.org/text.asp?2015/58/3/368/162903



   Introduction Top


Melanotic schwannoma is a rare pigmented nerve sheath tumor of schwannian cell origin. [1] The tumor arises from sympathetic nervous system commonly from the spinal or autonomic nerves near the midline. They can occur in unusual sites such as stomach, bone, soft tissue, heart, bronchus, liver, and skin. [2] Two variants have been described, psammomatous and nonpsammomatous. 50% of psammomatous tumors are associated with Carney syndrome. [2]


   Case Report Top


A 67-year-old male presented with a history of weakness and numbness in both lower limbs for 2 months with a progressive increase in severity. Magnetic resonance imaging showed an intradural, extramedullary lesion at D8-D12 level [Figure 1]a. Clinical examination revealed oral mucosa and abdominal skin pigmentation. Echocardiogram showed normal study. There were no signs and symptoms of endocrine overactivity. The patient underwent D8-D12 laminectomy. Grossly, the tumor tissue comprised of multiple brown to blackish soft tissue fragments [Figure 1]b. Intraoperative crush smears and frozen sections revealed diffuse sheets and fascicles of spindle cells with abundant coarse melanin pigment, obscuring cellular details with psammomatous calcification [Figure 2]a and b. Paraffin-embedded histopathology sections showed cells with oval to spindle nuclei, fine chromatin, inconspicuous to small nucleoli and eosinophilic cytoplasm with ill-defined cytoplasmic borders containing melanin pigment. The cells were predominantly arranged in fascicles with focal epithelioid pattern in lobules [Figure 3]a and b. The pigment was cleared by melanin bleach using potassium permanganate. Features of anaplasia like cellular pleomorphism, hyperchromasia or increased mitoses were absent. The sections also showed few psammoma bodies. Reticulin stain showed poor reactivity with focal pericellular pattern. Immunohistochemistry revealed strong positivity for S-100, vimentin, focal positivity for HMB-45, Leu-7 with negativity for cytokeratin and epithelial membrane antigen (EMA). Ki-67 labeling index was <1% [Figure 4]a-d. Based on clinical, radiologic, and histopathologic findings with immunohistochemistry correlation, the case was diagnosed as psammomatous melanotic schwannoma.
Figure 1: (a) Magnetic resonance imaging spine T1 postcontrast image showing intradural extramedullary enhancing lesion at D8-D12 level. (b) Gross appearance of the tumor showing multiple grayish black fragments


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Figure 2: Squash smear cytology: (a) Fascicles of spindle cells with abundant melanin pigment (H and E, ×10). (b) Cells with oval nuclei and intracytoplasmic melanin pigment without cytological atypia. Inset showing psammoma bodies (H and E, ×40)


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Figure 3: Histopathology sections showing (a) Fascicles of spindle cells with abundant melanin pigment (H and E, ×10). (b) Lobules of epithelioid appearing cells with round to oval nuclei, tiny nucleoli, and indistinct cytoplasmic borders. Cytologic atypia is absent (H and E, ×40)


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Figure 4: Immunohistochemistry (red indicates positivity. Chromogen used ultraview red, Ventana Company) (a) Strong and diffuse positivity for S-100. (b) Focal positivity for HMB-45. (c) Positivity for Leu-7 (d) low Ki-67 proliferation index


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   Discussion Top


Melanotic schwannoma is a rare variant of schwannoma arising from sympathetic nervous system. [1] It commonly occurs in the fourth decade of life. The tumor commonly arises from the spinal or autonomic nerves near the midline. Melanotic schwannomas are usually solitary and ovoid, but a multifocal nodular manifestation may be seen, in which case the tumor often is malignant. [1] The tumors generally are covered entirely or in large part by a thin fibrous membrane; their cut surface varies from gray to black. Two variants have been described, psammomatous and nonpsammomatous. Most melanotic schwannomas are characterized by plump spindled and epithelioid cells. Considerable histologic variation may be seen. The cells are disposed in lobules, nests, sheets, or somewhat fascicular arrangements and have indistinct cell borders, thus yielding a syncytial appearance. Nuclei are round to ovoid with delicate chromatin and small nucleoli. Melanin pigmentation is variable as is cytoplasmic volume. This rare tumor can cause diagnostic difficulties in imprint cytology or intraoperative squash smear due to cellular details masked by heavy melanin pigments. [3] Reticulin pattern is poor in this subtype. [2] Zhang et al. [4] in their study of 13 melanotic schwannomas observed cytoplasmic vacuoles, as a common finding mimicking adipocytes, which is not observed in our case. On Immunohistochemistry, the cells show strong positivity for S-100, vimentin, membranous staining for collagen IV with a variable positivity for Leu-7 (CD57) and melanocytic markers such as HMB-45, melan-A (MART-1). [1],[2] Ultrastructural studies show variably pigmented melanosomes with elaborate cell process characteristic of Schwann cells. The biologic behaviors of these tumors are difficult to predict, and metastases can occur in the absence of overt malignant features. Neither tumor size nor ploidy predicts malignant behavior. [5] Slightly over 10% of melanotic schwannomas follow a malignant course, [1] and those tumors show prominent nucleoli and frequent mitoses.

About 50% of psammomatous tumors are associated with associated with Carney syndrome. The mean age of Carney complex-affected patients is 22 years, a decade younger than for individuals with nonsyndromic melanotic schwannomas. [1] Components of the disorder include lentiginous pigmentation, blue nevi, myxomas of heart, skin, or breast; congenital osteochondromyxoma and endocrine overactivity. In our case, the patient had mucocutaneous pigmentation and psammomatous schwannoma, thus having two major criteria [6] to diagnose Carney syndrome, but the patient presented in the seventh decade. The patient underwent wide local excision and postoperative period was uneventful. The patient is on regular follow-up for >20 months, with no evidence of recurrence.

The differential diagnosis of melanotic schwannoma includes malignant melanoma and meningeal melanocytoma. [7] It is of great clinical significance that melanomas should be differentiated from melanotic schwannomas. In contrast to melanoma, the cells of melanotic schwannoma are often arranged in syncytium, and they generally exhibit a bland cytology with only slight cytologic atypia. Melanomas do not feature psammoma bodies. [1] Though melanocytic schwannomas express melanocytic markers, they are also positive for collagen IV, Leu-7 and Ki-67 index will be very low. Meningeal melanocytomas, which originate from leptomeninges, often feature whorling, lack atypia, but may exhibit perilobular basal lamina formation. They express melanocytic markers, but there is absence of meningothelial markers like EMA. [8]


   Conclusion Top


Melanotic schwannoma is a rare form of pigmented neural tumor. 50% of psammomatous variants are associated with Carney complex, so patients should be evaluated for the presence of other components. Complete surgical resection is essential to prevent recurrence. The biologic behavior varies among patients, so long-term follow-up is essential. The main differential diagnosis for this tumor is melanoma. In general, pigmented lesions of central nervous system are rare entities that may appear similar at both imaging and histologic evaluation. Immunohistochemistry has a limited role in the evaluation of these lesions. Knowledge of the clinical and pathologic spectrum of these lesions aids in the differential diagnosis.

 
   References Top

1.
Scheithauer BW, Woodruff JM, Spinner RJ. Peripheral nerve sheath tumors. In: Perry A, Brat DJ, editors. Practical Surgical Neuropathology. 1 st ed. Philadelphia,: Elsevier; 2010. p. 250-1.  Back to cited text no. 1
    
2.
Scheithauer BW, Louis DN, Hunter S, Woodruff JM, Antonesu CR. Schwannoma. In: Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, editors. WHO Classification of Tumors of the Central Nervous System. Lyon: IARC; 2007. p. 154.  Back to cited text no. 2
    
3.
Azarpira N, Torabineghad S, Sepidbakht S, Rakei M, Bagheri MH. Cytologic findings in pigmented melanotic schwannoma: A case report. Acta Cytol 2009;53:113-5.  Back to cited text no. 3
    
4.
Zhang HY, Yang GH, Chen HJ, Wei B, Ke Q, Guo H, et al. Clinicopathological, immunohistochemical, and ultrastructural study of 13 cases of melanotic schwannoma. Chin Med J (Engl) 2005;118:1451-61.  Back to cited text no. 4
    
5.
Shields LB, Glassman SD, Raque GH, Shields CB. Malignant psammomatous melanotic schwannoma of the spine: A component of Carney complex. Surg Neurol Int 2011;2:136.  Back to cited text no. 5
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6.
Pagon RA, Adam MP, Ardinger HH, Wallace SE, Amemiya A, Bean L JH et al., editors. GeneReviews ® . Seattle (WA): University of Washington, Seattle; 1993-2014. Available from: http://www.ncbi.nlm.nih.gov/books/NBK1116/.  Back to cited text no. 6
    
7.
Er U, Kazanci A, Eyriparmak T, Yigitkanli K, Senveli E. Melanotic schwannoma. J Clin Neurosci 2007;14:676-8.  Back to cited text no. 7
    
8.
Smith AB, Rushing EJ, Smirniotopoulos JG. Pigmented lesions of the central nervous system: Radiologic-pathologic correlation. Radiographics 2009;29:1503-24.  Back to cited text no. 8
    

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Correspondence Address:
Dr. Salapathi Shanmugam
Department of Histopathology, SRM Institute for Medical Sciences, Chennai, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0377-4929.162903

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

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