case_images: PMC9673151_01
case_images: The right finger had an unhealed incision without obvious
  exudation.
case_images: 1678-9946-rimtsp-64-S1678-9946202264076-gf01.jpg
case_images: PMC9673151_01_1678-9946-rimtsp-64-S1678-9946202264076-gf01.jpg
case_images: f1
case_images: Upon physical examination, the right finger had an unhealed incision without obvious exudation (Figure 1).
case_images: A) A histopathology examination revealed fibrous connective tissue
  hyperplasia, massive inflammatory cell infiltration, and granuloma
  formation; B) Ziehl-Neelsen staining revealed positive bacillus in the pus
  specimens.
case_images: 1678-9946-rimtsp-64-S1678-9946202264076-gf02.jpg
case_images: PMC9673151_01_1678-9946-rimtsp-64-S1678-9946202264076-gf02.jpg
case_images: f2
case_images: A histopathology examination revealed fibrous connective tissue hyperplasia, massive inflammatory cell infiltration, and granuloma formation (Figure 2A). Ziehl-Neelsen staining revealed positive bacillus in the pus specimens (Figure 2B).
case_images: A) Bacterial colonies were exposed to sunlight for 18 h; B) White
  bacterial colonies grow on Columbia blood agar; C) Bacterial colonies
  changed from white to yellow after 18h of sunlight exposure.
case_images: 1678-9946-rimtsp-64-S1678-9946202264076-gf03.jpg
case_images: PMC9673151_01_1678-9946-rimtsp-64-S1678-9946202264076-gf03.jpg
case_images: f3
case_images: Therefore, we used photochromogenicity to distinguish between the two (Figure 3A). In our case, the colonies turned yellow after 18h of incubation in the sun, which helped identify the species as M. marinum (Figure 3B and Figure 3C).