How long should one wait before biopsying a persistently palpable mass of early stage nodular lymphocte predominant Hodgkin lymphoma (NLPHL) after radiation?

There is no set time frame for biopsy. I will recommend a PET/CT 3 months post treatment before making a decision on biopsy . The sensitivity, specificity, PPV and NNP of PET in NLPHL is 99 - 100 % (Grellier et al. Eur. J. Nucl . Med. mol Imaging 2014 ).