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| Different forms of cutaneous tuberculosis | Histopathological features | Observation of AFB |
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| Well-formed granulomas with absence of caseous necrosis |
| Lupus vulgaris | epidermis may be atrophic or hypertrophic, featuring acanthosis, papillomatosis and even pseudo-epitheliomatous hyperplasia. Presence of well-formed tuberculous granulomas accompanied more often by Langhans giant cells, or foreign body-like granulomas in the reticular dermis. | infrequent |
| Lichen scrofulosorum | non-caseating, epithelioid cell granulomas in upper dermis and around dermal appendages | not seen |
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| Intermediate forms: granulomas with caseous necrosis |
| Tuberculosis verrucosa cutis | marked pseudoepitheliomatous hyperplasia of the epidermis with hyperkeratosis and dense inflammatory cell infiltrate consisting of neutrophils, lymphocytes, and giant cells. The presence of granulomatous infiltrates is a cardinal sign | can be seen |
| Primary cutaneous tuberculosis | it varies according to the time of inoculation; in recent lesions there is the presence of necrotizing neutrophilic infiltrate with numerous AFB. At a later stage there is organization of granulomas | decreased number |
| Acute miliary tuberculosis | skin consists of areas of an inflammatory infiltrate composed of lymphocytes, plasma cells, and neutrophils with focal superficial dermal areas of necrosis and abscess formation without true caseating granuloma. The presence of acid-fast bacilli with vascular thrombi is characteristic of these lesions | can be seen |
| Tuberculosis orificialis | there are tuberculoid granulomas, around a median, central, and superficial ulcer accompanied by caseous necrosis in the deep dermis | not usually found |
| Papulonecrotic tuberculid | lesions showed psoriasiform epidermal hyperplasia, and epithelioid granulomas with lymphocytes and Langhans giant cells with variable amounts of necrosis seen in the upper and mid dermis with a perifollicular distribution | not usually found |
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| Poorly formed granulomas with intense caseous necrosis |
| Scrofuloderma | Massive central necrosis with abscess formation and in many cases, suppuration, traces of granulomas can be observed at periphery of the lesions | may be found |
| Metastatic abscesses and gumma | Central ulceration with abundant caseous necrosis, surrounded by a rim of giant cells and macrophages can be observed | frequently detected |
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