Superficial mycoses
Tinea Versicolor
Tinea versicolor (or pityriasis versicolor) is a chronic 
recurrent condition involving the superficial layer (stratum 
corneum) of skin, caused by a lipophilic fungus Malassezia 
furfur.
Clinical Manifestations
It is characterized by flat-round scaly patches of hypo- to 
hyperpigmentation of skin (Fig. 58.1A).
 Lesions are non-inflammatory and non-pruritic (or 
rarely pruritic)
 Lesions can be mistaken for vitiligo, but the latter is not 
scaly
 Areas rich in sebaceous glands are commonly involved 
such as neck, chest, or upper arms
 Disease is more common in moist humid areas.
Other manifestations caused by Malassezia furfur 
include:
 Seborrheic dermatitis: It manifests as erythematous 
pruritic scaly lesions called dandruff in adults and cradlecap in babies. It can be severe in patients with advanced 
AIDS
 Atopic dermatitis
 Folliculitis (hair follicle infection)
 Disseminated infection can occur rarely.
Laboratory Diagnosis
Diagnosis of tinea versicolor is largely made clinically. The 
laboratory diagnostic methods are as follows:
 Direct microscopy: Skin scrapings are examined 
microscopically after treating with 10% KOH. Mixture of 
budding yeasts and short septate hyphae are seen, described 
as spaghetti and meatballs appearance (Fig. 58.1B)
 Culture:Malassezia furfur being lipophilic, SDA with olive 
oil overlay is the ideal media for culture. Typical ‘fried egg’
colonies appear after incubating for 5–7 days at 32–35°C
 Urease test: It gives a positive urease test
 Wood’s lamp examination: Under Wood’s lamp, the 
scaly lesions show golden yellow fluorescence.Tinea Nigra
It is characterized by painless, black, non-scaly patches 
present on palm and sole; more commonly in females. It 
is caused by Hortaea werneckii. It is a black-colored yeast 
like fungus.
Piedra
Piedra is characterized by nodule formation on hair shaft, 
which may be either black or white in color.
White Piedra 
Here, white nodules are formed on the hair shaft, which are 
less firmly attached. 
 Agent: Trichosporon beigelii
 Identifying feature: T. beigelii is an urease positive, yeast 
like fungus; produces creamy white colonies, containing 
hyaline septate hyphae intervening with rectangular 
arthrospores (Fig. 58.1C).
Black Piedra
It is characterized by formation of black nodules, which are 
firmly attached to the hair shaft (Fig. 58.1D).
 Agent: Piedraia hortae
 Identifying feature: It is a phaeoid fungus; produces 
reddish brown colonies; containing dark brown thick 
septate hyphae with ascus containing ascospores.
Dermatophytoses
Dermatophytoses (or tinea or ringworm) is the most 
common superficial mycoses affecting skin, hair and nail; 
caused by a group of related fungi (called dermatophytes) 
that are capable of infecting keratinized tissues. These 
include:
 Trichophyton species: Infect skin, hair and nail
 Microsporum species: Infect skin and hair
 Epidermophyton species: Infect skin and nail.
Depending on the usual habitat (humans, animals, or soil), 
dermatophytes are classified as follows (Table 58.1):
 Anthropophilic: These are the fungal agents exclusively 
infect humans
 Zoophilic: They infect animals as well as birds
 Geophilic: These fungal species are frequently isolated 
from soil.
Pathogenesis
Dermatophyte infection is acquired by direct contact with 
soil, animals or humans infected with fungal spores. Then 
the spores are carried to different areas due to scratching 
of the inoculated site. Predisposing factors include moist 
humid skin and tight ill-fitting underclothing.
 Skin: Dermatophytes grow in a centrifugal pattern 
in the stratum corneum; leading to the formation of 
characteristic well-demarcated annular- or ring-shaped 
pruritic scaly skin lesions with central clearing and raised 
edges. Scaling, erythema, and rarely blister formation 
may occur
 Nails: They invade the nails through the lateral or super-
ficial nail plates and then spread throughout the nails
 Hair shafts: Dermatophytes can invade within the hair 
shaft or may be found surrounding it. Hair becomes 
brittle and areas of alopecia may appear. A deep and 
persistent suppurative folliculitis may be produced; 
called as Majocchi granuloma
 Lesions are not produced by the tissue invasion by the 
fungi per se; but in response to the host’s inflammatory 
reaction elicited by the fungal antigens
 Males are more commonly infected than females as 
progesterone is inhibitory to dermatophyte growth
 Severity depends on the infecting fungi, immune status 
of the host and the site of lesion
 Anthropophilic dermatophytes are the most 
common dermatophytes infecting humans. They 
cause relatively mild and chronic lesions but respond 
poorly to treatment In contrast, geophilic and zoophilic species, being 
less adapted to human hosts, produce more acute 
inflammatory response and severe infections; but 
they tend to resolve more quickly. 
Clinical Types
Depending on the site of involvement, various clinical 
types of dermatophytic or tinea or ring worm infections 
are produced (Table 58.2). Incubation period is about 1–2 
weeks. 
Dermatophytid or Id Reaction
Occasionally, hypersensitivity to dermatophyte antigens 
may occur, which leads to appearance of secondary 
eruption in sensitized patients because of circulation of 
allergenic products. However, these lesions are distinct 
from the primary ringworm lesions as they occur distal to 
primary site and fungal culture often turns negative.Laboratory Diagnosis
Woods Lamp Examination
Certain dermatophytes fluoresce when the infected lesions 
are viewed under Wood’s lamp. It is usually positive for 
various Microsporum species and Trichophyton schoenleinii. 
Other dermatophytes do not fluoresce under Wood’s lamp. 
Fluorescence is due to the presence of pteridine pigment 
in cell wall.
Specimen Collection
Skin scrapings, hair plucks (broken or scaly ones) and nail 
clippings are obtained from the active margin of the lesions 
and are kept in folded black paper. Hair should be plucked, 
but not cut.
Direct Examination
The specimen is mounted in KOH (10% for skin scrapings 
or hair, 20–40% for nail clippings) or calcofluor white stain 
and is examined for the presence of thin septate hyaline 
hyphae with arthroconidia (see Chapter 6, Figs 6.2A and B). 
When hair is involved, the arthroconidia may be found on 
the surface of the hair shaft (ectothrix) or within the shaft 
(endothrix) (Figs 58.3A and B).
Culture
Specimens should be inoculated onto SDA containing 
cycloheximide and incubated at 26–28°C for 4 weeks. 
Potato dextrose agar is used to stimulate the sporulation. 
Identification is made by:
 Macroscopic appearance of the colonies such as—rate 
of growth, texture, pigmentation, colony topography Microscopic appearance: The colonies are teased and 
LPCB mount is made to demonstrate the hyphae and 
spores (or conidia):
 Conidia: Two types of spores or conidia are observed 
such as small unicellular microconidia, and large 
septate macroconidia; both are used for identification 
of species (Table 58.3 and Figs 58.3C to F)
 Special hyphae: Dermatophytes possess thin septate 
hyaline hyphae; some species have specialized 
hyphae such as spiral hyphae, racquet hyphae and 
favic chandeliers (Figs 58.3G to I).
Identification features (macroscopic and microscopic) 
of commonly encountered dermatophyte species is given 
in Table 58.4.
Other Methods of Diagnosis
Apart from culture, there are several other methods 
available for identification of dermatophytes such as: Hair perforation test: It is positive for Trichophyton 
mentagrophytes and Microsporum canis. The test is 
performed by inoculating a colony into a petri dish 
containing water, yeast extract, and hair. Fungi pierce 
the hair producing wedge-shaped perforations
 Urease test: Trichophyton mentagrophytes is urease 
positive
 Dermatophyte test medium and Dermatophyte 
identification medium: They are used for presumptive 
identification. These tests are based on color change in 
the medium due to production of alkali metabolites
 Molecular methods: PCR can be used to detect species 
specific genes (e.g. chitin synthase gene)
 Skin test: It is done for detecting hypersensitivity to 
dermatophyte antigen (trichophytin).