Some biological abnormalities may be supportive of the diagnosis (lymphopenia, inflammatory signs, polyclonal hypergammaglobulinemia, hypercalcemia, elevated ACE, elevated beta-2 microglobulin, CSF hyperproteinorachia with lymphocytic pleocytosis, and increased ACE level), especially when associated with a negative tuberculin skin test in a previously vaccinated patient [14]. Here, B2M is linked to lymphopenia.