Unilateral cervical lymphadenopathy in a pediatric patient with a bluish hue over the node and granulomatous biopsy; which organism is most likely?

• A. Staphylococcus aureus
• B. Bartonella henselae
• C. Mycobacterium avium-intracellulare
• D. Streptococcus pyogenes

Answer: (C)

Unilateral cervical lymphadenopathy with a bluish overlying skin in a child, plus granulomatous inflammation on biopsy, points to mycobacterial lymphadenitis. Among non-TB mycobacteria, Mycobacterium avium-intracellulare is the classic cause of this pattern in otherwise healthy children. These infections typically present as a solitary, slowly enlarging, nontender neck node with some discoloration of the skin. Biopsy shows granulomatous inflammation, and acid-fast bacilli can often be found on special stains.

In contrast, staphylococcal or streptococcal infections cause acute, painful, erythematous, sometimes fluctuant nodes without a granulomatous pattern. Bartonella henselae (cat-scratch disease) can cause unilateral cervical lymphadenopathy, but its presentation is usually more subacute with fever and the histology isn’t the granulomatous pattern described here.