Does Pathological Variability in Paediatric Nodular Lymphocyte Predominant Hodgkin Lymphoma Have Clinical Prognostic Significance?

Question: Although the pathology of typical nodular lymphocyte predominant Hodgkin lymphoma (NLPHL) is well defined, the literature describes atypical cases with diffuse, interfollicular and T cell-rich patterns, often associated with IgD expression in the LP cells. We have examined a group of paediatric NLPHL patients to determine if atypical histology correlates with treatment outcome.

Methods: We reviewed the pathology of 23 cases of early stage paediatric NLPHL and assessed disease recurrence and disease progression. The cases were stained with a standard panel of antibodies and examined by an experienced haematopathologist. Treatment consisted of either surgical excision biopsy for patients with resectable stage IA NLPHL or 3 courses of low intensity chemotherapy comprising cyclophosphamide, vinblastine and prednisolone for those with unresectable stage IA NLPHL or IIA NLPHL. All patients underwent response assessment with cross sectional CT/MRI with or without FDG PET at the end of therapy.

Results: The pathology was typical in 16 cases (70%) and atypical in 7 cases. Three patients showed a diffuse T-cell rich pattern, two had interfollicular disease, one demonstrated focal NLPHL on a background of transforming germinal centres and one showed a separate EBV-positive B cell proliferation. IgD positive LP cells were present in all 6 of the atypical cases tested, but 9 of 11 typical NLPHL cases (83%) also showed this feature. Follow-up on 5 patients with atypical histology showed that two achieved a complete remission and remain in remission. One patient with diffuse NLPHL only achieved a partial remission. The remaining two patients are still receiving first line treatment. All of the twelve patients with typical histology followed-up so far have achieved complete remission and continue to remain in remission.

Conclusion: Although numbers are small, we found that both atypical NLPHL histology and IgD expression by LP cells was frequent in this group. Neither feature appeared to have a marked prognostic significance in the short term, but longer clinical follow-up on the atypical cases will be of interest.