Giant malignant peripheral nerve sheath tumor of the scalp

Abstract

Herein, we describe a rare case of giant malignant peripheral nerve sheath tumor of the head in a 38-year-old Japanese man. The tumor measured 210 mm at its largest diameter and was ulcerated, hemorrhagic, multilocular and non-mobile. It should be noted that the patient stubbornly refused to see a doctor for a long time, resulting in the extreme growth of the tumor. We suspect a psychological basis for this behavior. Dermatohistopathological findings of the biopsy indicated ancient schwannoma and total excision was therefore performed. However, after 4 months, the patient developed multiple metastases and died. Post-mortem skin biopsy revealed features of malignant peripheral nerve sheath tumor. We performed immunohistochemical studies on the primary and recurrent lesions and concluded that there was a difference in the expression of Ki67 and p16. We propose that the expressions of Ki67 and p16 should be checked for all lesions of peripheral nerve sheath tumor for distinguishing benign from malignant forms.

Diffuse scalp malignant peripheral nerve sheath tumor with intracranial extension in a patient with neurofibromatosis type 1

“…Of these, none mentioned a relationship with NF1. 2,[4][5][6] Although MPNSTs do not have specific imaging features, CT scans and MRI assessment are useful tools to detect the relationship with surrounding tissues. 7 Of the four previously reported patients with scalp MPNST, radiological assessment found three to have cranial destruction and intracranial extension; only one patient had neither cranial destruction nor intracranial extension.…”

“…7 Of the four previously reported patients with scalp MPNST, radiological assessment found three to have cranial destruction and intracranial extension; only one patient had neither cranial destruction nor intracranial extension. 5 Given that cranial destruction can be produced by other types of tumors, including a giant benign tumor, this is not a reliable indicator of MPNST. However, MPNSTs can increase in size rapidly over a short time, and this generally indicates malignant transformation 8 .…”

“…Some authors suggest that p16 can be used to differentiate MPNST from benign peripheral nerve sheath tumors (BPNST), as p16 is expressed in BPNST but not MPNST. 5 Agesen et al felt that the gross rearrangements of the p16(INK4A) gene observed in most patients with MPNST explained the absence of the encoded protein of the p16 gene in these tumors. 11 Recently, Fang et al examined of primary, metastatic and recurrent MPNSTs with underlying NF1 and found deletions of 9p, 12q21-q32 and complete loss of the X-chromosome, as well as gains in 17q25.…”

A Case of Malignant Peripheral Sheath Tumor Arising from Neurofibromatosis Type 1

“…The histogenesis of MPNST is still unclear, and at times the features show overlap with other soft tissue sarcomas. Clinically, MPNSTs occur in adults 20 to 50 years of age as huge masses, at times arising from preexisting neurofibromas, and are most commonly located on the proximal limbs, head and neck, and trunk, as well as the retroperitoneum, mediastinum, and viscera 10 . The diagnosis of MPNST has always remained a challenge due to the lack of standardized diagnostic criteria, and its tendency to show overlap with over fibrous or neural crestderived tumors 9 .…”

“…There are hyperchromatic nuclei and widespread, multiple mitotic figures. The differential diagnosis of MPNST and benign schwannoma can be confusing; necrotic foci, atypical mitoses, and the lack of differentiated cells all indicate the former diagnosis 10 . These three features determine the histologic grade of the tumor, which in our case was grade 3.…”