Final answer:
The nurse practitioner would anticipate the additional finding of supraclavicular lymphadenopathy.
Step-by-step explanation:
The additional finding that the nurse practitioner would anticipate in the case of a 20-year-old male presenting with fatigue, anterior and posterior cervical lymphadenopathy, and right and left upper quadrant abdominal tenderness, and lymphocytosis with reactive forms on the white blood cell differential is Supraclavicular lymphadenopathy. Supraclavicular lymphadenopathy refers to the enlargement of lymph nodes located above the clavicles, which can be a sign of malignancy or metastasis.