Can 2 biopsies done at same time rule out cutaneous t-cell lymphoma completely? if symptoms point to ctcl but biopsy was neg when should we re-biopsy?

Yes: Without more information i would default to another biopsy. Early diagnosis can be helpful. I would not delay.

Not Completely: The average number of biopsies to completely diagnose CTCL is about 6. That said, if the type of CTCL is the common type, mycosis fungoides(MF), and not mimics of MF, then 1 or 2 biopsies could be diagnostic especially if typical patches, plaques of CTCL. If the latter, ancillary tests including molecular clonality T cell test are crucial for diagnosis excluding mimics. Rebiopsy in about 3 mos.