Primitive neuroectodermal tumor (peripheral type)

Group, very rare neuroectodermal tumors (PNET) with variable differentiation, which can occur both as tumors of the central nervous system and peripherally outside the CNS (also cutaneous/subcutaneous). All tumors of this group have a characteristic reciprocal chromosome translocation t(11;22) (q24;q12) in common. Peripheral tumors of this group also include:

• the extraskeletal Ewing sarcoma
• peripheral neuroepitheliomas
• the ascine tumor (PNET of the chest wall).

Age at first manifestation between 16 and 61 years, average 25 years. w>m;

Extremities and trunk

The clinical findings are not very specific. Deep-seated soft tissue masses are usually impressive. They are clinically diagnosed as carcinomas or malignant melanomas.

Lobular or trabecular structure of cutaneously-subcutaneously localized parenchyma masses with densely packed cells with blistered cytoplasm and small round chromatin-tight nuclei. Zal-rich mitoses detectable. Noticeable are recurrent necroses. The parenchyma is reactive for the MIC-2 antigen (CD99), HBA71 or O13. The reactivity for NSE is inconstant.

1. Bahk WJ et al (2010) Primary cutaneousEwing's sarcoma/primitive neuroectodermal tumor manifesting numerous small and huge ulcerated masses: its complete remission by chemotherapy and magnetic resonance imaging findings. Skeletal radiol 39:595-600.
2. Boland JM et al (2013) Cutaneous neoplasms showing EWSR1 rearrangement. Adv Anat Pathol 20:75-85.
3. Kalra S et al (2010) Primary cutaneous ewing's sarcoma/primitive neuroectodermal tumor: report of the first case diagnosed on aspiration cytology. Acta Cytol 54:193-196.
4. Liu Y et al (2011) Primary cutaneous peripheral primitive neuroectodermal tumor with multiple papules and nodules. Eur J Dermatol 21:786-787.
5. Morrison LK et al (2011) Persistent primary cutaneous primitive neuroectodermal tumor 4 years after chemotherapy. J Am Acad Dermatol 65:440-441.
6. Oliveira Filho Jd et al (2014) Primary cutaneous Ewing sarcoma--case report. On Bras Dermatol 89:501-503.
7. Shingde MV et al (2009) Primary cutaneous Ewing sarcoma/primitive neuroectodermal tumour: a clinicopathological analysis of seven cases highlighting diagnostic pitfalls and the role of FISH testing in diagnosis. J Clin Pathol 62:915-919.