The given patient has pemphigus vulgaris. The Tzanck test/Tzanck Smear, is scraping of an ulcer base to look for Tzanck cells. It ia a simple test which can be done bedside in a patient of pemphigus. It shows numerous acantholytic keratinocytes. - rounded and more or less uniform in size, with a relatively large nuclear : cytoplasmic ratio with a perinuclear pale halo, with the peripheral pa of the cell staining more darkly. Skin biopsy and immunofluroscence is more conclusive but is a laboratory test.