Case 174. 
Malassezial folliculitis (pityrosporum folliculitis) (39 y-o M)
         
   
Eruptive hair follicle lesions on the tatooed chest wall (biopsy)
   
         
   
Key words : Malassezia furfur, folliculitis, tinea versicolor
   
     
 
     
Erythematous follicular papules are seen on the tatooed chest wall. Malassezia furfur (M. globosa) was isolated from the lesion.   Inflammatory cells and basophilic granular debris are present in the dermis adjacent to the point of rupture of the hair follicle. Granulomatous reaction is (suppurative granuloma) associated (HE, low power).
     
 
     
Features of granulomatous folliculitis with central abscess are evident. It is not easy to identify transparent yeasts within the lesion (HE, high power).   The 1:500 diluted patient's own serum is reactive to small yeasts present within the abscess cavity (indirect immunoperoxidase).
     
 
     
Reference case 174A
Malassezia furfur incidentally identified in the dilated hair follicle adjacent to the nevocellular nevus biopsied from a 23 y-o female (HE). M. furfur (M. globosa or M. sympodialis in the recent terminology) is a dimorphic lipophilic fungus, and is a normal inhabitant at the infundibulum of the hair follicle of the upper trunk and upper arm.
  Reference case 174A
Malassezia furfur seen adjacent to nevocellular nevus (PAS). Budding yeasts (blastoconidia) and short hyphae (pseudomycelia) are observed in the cornified layer, giving a so-called "spaghetti and meat balls" appearance. The mycelial form is not so clear in the state of normal flora.
     
 
     
Reference case 174B
Tinea versicolor (pityriasis versicolor) on the chest wall of a 43 y-o male (gross findings). The affected skin varies in color from red-brown to white. The white skin becomes pigmented, while the black skin becomes depigmented. Hence the name "versicolor" (versi = version or change).
  Reference case 174B
Tinea versicolor (pityriasis versicolor) on the arm of the same patient (gross findings). The fungi needs the sebum to grow, so that the seborrheic skin is the site of inhabitance. Mycelial form is evident in the lesion of tinea versicolor.