Malignant peripheral nerve sheath tumors of the skin

Cutaneous Malignant Peripheral Nerve Sheath Tumor

Cutaneous malignant peripheral nerve sheath tumors (MPNSTs) are rare sarcomas of neuroectodermal origin arising in the dermis and/or subcutis. In contrast with their deep soft tissue and visceral counterparts, cutaneous MPNSTs are rarely associated with neurofibromatosis type 1. Two main subtypes of cutaneous MPNST can be distinguished histologically: conventional (ie, spindle cell) and epithelioid MPNST. The 2 subtypes also differ in predilection for deep versus superficial locations, association with preexistent benign peripheral nerve sheath tumors and S100 immunohistochemistry. Herein, we review current knowledge of cutaneous MPNST and discuss its differential diagnosis.

Sarcomas cutâneos primários

Os sarcomas com apresentação cutânea primária são tumores raros e de grande heterogeneidade histológica. Com a evolução da oncologia cutânea e da cirurgia dermatológica, os dermatologistas têm sido cada vez mais requisitados para o diagnóstico e orientação terapêutica de tumores menos freqüentes. Este artigo de revisão analisa os sarcomas cutâneos primários observando suas características clínicas, etiopatogênicas e histológicas, bem como aspectos do tratamento e evolução. Enfatiza os sarcomas de maior relevância para o dermatologista, como angiossarcoma, dermatofibrossarcoma protuberans, fibroxantoma atípico, leiomiossarcoma, lipossarcoma, tumor maligno de bainha de nervo periférico e sarcoma epitelióide. O sarcoma de Kaposi não é abordado devido a suas características individuais específicas.

Multidisciplinary management of head and neck sarcomas

BACKGROUND

Head and neck sarcomas are extremely rare. This article reviews the management and outcomes in a multidisciplinary clinic.

METHODS

The records of 41 male and 19 female patients (mean age, 50 years) were reviewed. Forty percent underwent surgical resection only, 35% underwent surgery and adjuvant therapy, and 25% underwent radiotherapy and/or chemotherapy without surgery. Seventy-one percent had complete histologic clearance.

RESULTS

The mean follow-up was 3 years and 10 months, with an overall 5-year survival rate of 60%. Completeness of surgical excision was highly significant in determining 5-year local control (p < .025), and the addition of adjuvant radiotherapy had a major effect on local control, but only if complete surgical clearance had been achieved (p < .025). As expected, patients with more aggressive tumors had a significantly poorer overall prognosis, and achieving local control led to an enhanced 5-year survival (p < .025).

CONCLUSION

These tumors are best managed in multidisciplinary clinics, and the mainstay of treatment is wide local excision and planned postoperative adjuvant radiotherapy.

Malignant peripheral nerve sheath tumour metastasising to the parotid gland

Two rare cases of metastases from malignant peripheral nerve sheath tumours (MPNST) of the head and neck are described. The initial lesions were superficial, but despite early diagnosis and complete excision, they metastasised to the ipsilateral parotid gland. Both underwent further complete excision and neither metastatic lesion showed progression in grade. One patient is alive, however, the other died of widespread metastases. There are no other reported cases of these sarcomas in the head and neck metastasising to the parotid gland.

Cutaneous melanoma with myxoid features: twelve cases with differential diagnosis

Substantial myxoid change can occur in malignant melanoma, but its importance in primary disease has not been systematically evaluated. This report describes the clinical, microscopic, histochemical, and immunohistochemical findings in 12 patients with primary cutaneous malignant melanoma with myxoid features. The tumors presented as solitary lesions situated on the limbs (six lesions), trunk (four lesions), and head and neck (two lesions). The patients included six women and six men, whose ages ranged from 26 to 95 years, with a mean of 63 years. Breslow thickness varied from 0.48 mm to more than 12 mm, with a mean of more than 3.2 mm. Clinical follow-up for an average of 22 months showed one local recurrence, but no evidence of metastases yet. In all cases, there was a combination of myxoid and nonmyxoid areas. A minimum of 15% myxoid cross-sectional area was required for inclusion in the study, and up to 80% was observed. The pale blue mucin identified on hematoxylin and eosin staining was sensitive to hyaluronidase and positive for alcian blue in the 10 cases stained. Immunohistochemical staining was positive for S-100 in all 9 cases stained, positive for HMB-45 in 9 (90%) of 10, and negative for cytokeratin in all 9 cases in which myxoid melanoma remained in the block after previous sections. The presence of myxoid stroma did not define a biologically significant subgroup of melanoma. Only in cases with extensive (>50%) myxoid stromal effacement of the melanoma was there a major diagnostic hurdle. The diagnosis of primary cutaneous melanoma with myxoid features was seldom as problematic as metastatic myxoid melanoma. Positive S-100 stains, negative cytokeratin immunohistochemical stains, and hyaluronidase-sensitive alcian blue staining assisted in the diagnosis of this entity.

Fibrosarcomatous ("high-grade") dermatofibrosarcoma protuberans: clinicopathologic and immunohistochemical study of a series of 41 cases with emphasis on prognostic significance

The fibrosarcomatous variant of dermatofibrosarcoma protuberans (FS-DFSP) represents an uncommon form of DFSP, in which the prognostic influence of the fibrosarcomatous component is still debated. We analyzed the clinicopathologic and immunohistochemical features in a series of 41 patients. Patient age ranged from 8 to 87 years (median, 48 years), and 19 patients were female. Twenty five lesions were seen on the trunk, 6 on the upper limbs, and 4 on the lower limbs, and five neoplasms were located in the head/neck region; in one case, exact anatomic site was unknown. Twenty seven tumors involved purely dermal and subcutaneous tissues, in 10 cases, deeper structures were also involved, 1 case arose in the breast, and, in 3 cases, it was impossible to define exact depth of the lesion. Preoperative duration ranged from 1 month to 60 years (median, 3 years). Twenty six tumors were excised locally with clear margins, 7 were treated by wide excision, 3 by incomplete excision, and, in 4 patients, the lesion was shelled out. In one case, exact treatment was unknown. In addition, radiotherapy was administered in three cases and chemotherapy in one case. Histologically, the lesions showed areas of typical, low-grade DFSP adjacent to fibrosarcomatous areas. In four cases, a previously ordinary DFSP recurred as pure fibrosarcoma, in two cases, local recurrence of FS-DFSP showed features of ordinary DFSP. Fibrosarcomatous change was more common in the primary (de novo) lesions than in recurrent lesions (3.6:1). Proportion of fibrosarcoma varied between < 30% in 6 cases to > 70% of tumor tissue in 21 cases. An abrupt transition between both components was seen in 19 cases. The fibrosarcomatous component showed focal necrosis in seven cases and showed a higher mitotic rate in comparison with ordinary DFSP areas (mean, 13.4 versus 2.3 mitoses in 10 high-power fields). Additional histologic features included progression to pleomorphic sarcoma in 2 recurrent cases, melanin-pigmented cells (Bednar FS-DFSP) in 1 case, focal myxoid change in 13 cases, plaque or keloidlike hyalinization in 3 cases, and myoid bundles and nodules in 9 cases. Immunohistochemically, tumor cells in DFSP areas stained positively for CD34, whereas, in FS-DFSP areas, only 15 out 33 cases were positive for CD34. Follow-up in 34 of 41 patients (mean, 90 months; median, 36 months) revealed local recurrence in 20 patients (58%) (recurrence occurred in 5 patients on two or more occasions). Metastases (5 lung, 1 bone, and 1 soft tissue) were seen in 5 patients (14.7%), and 2 patients have died of tumor to date (5.8%). Necrosis, high mitotic rate (> 10 mitoses per 10 high-power fields), and presence of pleomorphic areas in FS-DFSP tended to be related with poor clinical outcome, but no statistically significant association was detected. Fibrosarcomatous change in DFSP represents a form of tumor progression in DFSP and is associated with a significantly more aggressive clinical course than in ordinary DFSP, indicating a possible need for treatment intensification in such cases.

Desmoplastic melanoma of the vulva

The clinical and pathological features of a nonulcerated desmoplastic melanoma in the vulva of a 52-year-old woman are presented. Pleomorphic neoplastic spindle cells, fibroblasts and collagen formed a poorly demarcated 18 mm dermal mass. No adjacent intraepidermal component was seen. Immunoreactivity was demonstrated for S100 protein, vimentin, neuron-specific enolase and actin, but not for HMB-45, CAM 5.2, cytokeratin, epithelial membrane antigen, desmin or CD34. Electron microscopic examination was noncontributory. Treatment included a left hemivulvectomy with ipsilateral groin node dissection followed by radiotherapy. The tumor recurred six weeks later and was unresectable. The patient is alive with symptoms nine months after presentation. This is the first case report of a vulvar desmoplastic melanoma without neural involvement or an intraepidermal component. The variable tumor cytomorphology, nonspecific immunohistochemical and ultrastructural features render a diagnosis more difficult than with other primary cutaneous melanomas.

Malignant peripheral nerve sheath tumor of the skin: a superficial form of this tumor

A case of malignant peripheral nerve sheath tumor (MPNST) of the skin, which is a superficial form of this type of tumor, is described. Although our patient did not present the usual diagnostic criteria for MPNST, the clinicopathologic findings for both the initial and recurrent tumors were compatible with those of the ordinary type of this tumor and not with those of neurotropic melanoma or cellular schwannoma. The recurrent tumor presented progression compared to the low grade malignancy in the original tumor. Perhaps because of the superficial location of the tumor our patient showed an unexpected favorable outcome in spite of repeated recurrences. Reports indicate that, of the superficial forms, the ordinary type is still less frequently encountered than the epithelioid type. We also discuss the differentiation between MPNST of the skin and neurotropic melanoma.