Paediatric Peripheral Primitive Neuroectodermal Tumour - A Clinico-Pathological Study from Southern India

Abstract

Introduction: Primitive Neuroectodermal Tumour (PNET)/Ewing Sarcomas (ES) are aggressive childhood malignancies with neuroectodermal differentiation.

Aim: To study the clinical presentation, morphology, Immun-ohistochemistry (IHC), management and outcome of all the cases of paediatric pPNET/ES reported in our tertiary care centre over a period of six years.

Materials and methods: This was a retrospective study conducted at Sri Ramachandra Medical College and Research Institute, Chennai, India. All biopsy proven cases of peripheral PNET/ES, in patients less than 18 years of age for a period of six years were included in this study. The corresponding clinical details regarding initial presentation, treatment and follow up were retrieved from the case files and analysed. Survival rate was calculated and Kaplan-Meier survival curve was plotted.

Results: We describe eleven cases of paediatric peripheral PNET/ES. The mean age at presentation was 94.08 (±58.27) months with a male/female ratio of 1.2:1. About 27.3% cases, all male with a mean age of 140 months at presentation, had distant metastasis during initial diagnosis. Biopsy showed small round blue cell morphology on light microscopy. IHC revealed strong membranous staining for CD99 in all cases. All children were treated with neo-adjuvant chemotherapy and then surgery, followed by radiotherapy if indicated. The cases were followed up for a mean duration of 20.82 months (ranging from one to 66 months). Nine children are doing well on follow up (81.8% survival rate). Two cases with metastasis at initial presentation died. Patients with metastatic disease exhibited a mean duration of survival of 9.66 (±7.24) months and those with localized disease exhibited a mean duration of survival of 25 (±22.88) months.

Conclusion: Metastasis at diagnosis is the single most important factor affecting prognosis. This was reflected in the present study where cases with metastasis exhibited a short mean duration of survival when compared to localized disease. It is likely that many cases of PNET/ES were not accurately identified in the past as IHC plays a vital role in the diagnosis of these small round blue cell tumours. IHC in adjunct with molecular studies has improved diagnostic accuracy. Multidisciplinary management and good supportive care when the lesion is localized has lead to improved survival.

Keywords: CD99; Children; Ewing sarcoma; Survival.

[Table/Fig-2]:

Light microscopy shows sheets of monotonous small round blue cells (Haematoxylin and Eosin, 20X).

[Table/Fig-3]:

IHC shows diffuse membranous positivity for CD99 (10X).

[Table/Fig-4]:

Kaplan-Meier survival curve for localized and metastatic pPNET.