This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacterial Infection of Skin, Subject name: Skin
Tuberculous gumma (scrofuloderma) seen mostly on: 
Select and explain. 
A. Trunk, B. Any part of body, C. Extremities, D. Face
A: Trunk
Answer: A: Trunk 
Explanation: Ans: a (Trunk)Ref: IADVL, Vol. 1, 3rd ed. pg. 244Tuberculous gumma is a skin condition that results from haematogenous dissemination of mycobacteria from a primary focus, resulting in firm, nontender erythematous nodules that soften, ulcerate, and form sinuses.We could not find out a reference as to the commonest site of the TB gumma, but most texts show pictures of tuberculous gumma over the back of trunk. So we think that might be the answer.Scrofuloderma is a skin condition caused by tuberculous involvement of the skin by direct extension, usually from underlying tuberculous lymphadenitis.The most common site is the neck region. Tuberculids develop as a hypersensitivity response to a tuberculous foci in the body.Types of cutaneous TB1. Exogenous source Tuberculous chancre Lupus vulgaris2. Endogenous source Hematogenous/ lymphatic spreadLupus vulgarisAcute military tuberculosis of the skinTuberculous gummaContiguous spread/ auto inoculationScrofulodermaOrificial tuberculosis3. TuberculidsProbable tuberculidsLichen scrofulosorumPossible tuberculidsErythema induratumErythema nodosumFormer tuberculidsLichenoid tuberculidRosacea like tuberculidLupus miliaris disseminates facei