A 15 year old boy presented with multiple hypoaesthetic macules with sloping edge, seen on the face, trunk and arms. Histopathologic examination of lesion shows numerous bacilli and granulomatous infiltration. What is your diagnosis?
**Core Concept:** Granulomatous inflammation and histopathology findings are used to diagnose certain diseases. Granulomas are collections of macrophages, T cells, and neutrophils surrounding a central focus, usually an infected or irritant foreign body.
**Why the Correct Answer is Right:** The correct answer is tuberculosis (TB) because it is a granulomatous disease caused by the bacterium Mycobacterium tuberculosis. TB typically affects the lungs and can involve other organs as well. In this case, the patient presents with multiple hypoaesthetic macules, which are characteristic skin findings in cutaneous TB. Histopathology reveals numerous bacilli and granulomatous infiltration, confirming the diagnosis.
**Why Each Wrong Option is Incorrect:**
A. Leprosy: This is a granulomatous disease caused by Mycobacterium leprae. The clinical presentation and histopathology findings differ from TB.
B. Syphilis: Syphilis is a sexually transmitted infection caused by Treponema pallidum. The clinical presentation and histopathology findings are distinct from TB.
C. Infectious mononucleosis: This is a viral infection caused by Epstein-Barr virus. The clinical presentation and histopathology findings are different from TB.
D. Erythema nodosum: This is a subcutaneous panniculitis characterized by tender erythematous nodules. The histopathology findings are distinct from TB.
**Clinical Pearl:** Cutaneous TB should be considered in patients presenting with skin lesions and granulomatous infiltration, especially in endemic areas. Diagnosis can be confirmed by histopathology and culture. Early diagnosis is crucial, as TB treatment is effective and life-saving.