The most important
superficial mycoses is dermatophytosis, a clinical entity caused by a group
of related filamentous fungi - Dermatophytes, of the genera Epidermophyton ,
Microsporum and Trichophyton.
Diseases produced by
the dermatophytes occur worldwide and are known as tineas, or ringworm.
appearances are variable and depend on a number of factor:
(i) Species of fungus
(ii) Site of infection
(iii) Immunological status of
(iv) Use of topical steroid.
following use of topical steroids have been called 'tinea incognito'.
tinea of the head , scalp, eye-brow, and eyelash).
Kerion is a
boggy violaceous inflammatory area of dermal suppuration and folliculitis.
Favus is a chronic infection of the scalp and rarely of the glaborous skin
which is usually acquired in childhood.
2) Tinea Faciei : Rare variant
presenting as a facial erythema with scaling
3) Tinea corporis (of the body)-
The term 'radiation port dermatophytosis'- is used for cases of tinea
corporis localized to irradiated skin.
4) Tinea cruris
(of the groin)- Occurs exclusively in males. Have been noted in
patients with AIDS.
Diaper dermatitis is a variant which predominantly affects infants.
5) Tinea Pedis (of the foot) - Common
Fungal infection of the nail. The lesion presents as thickening,
discoloration, and deformity of the nails. Fungal organisms are
present in the deeper portions of the nail plate and in the hypertrophic
nail bed. PAS- stain is used to demonstrate the fungal elements.
granuloma: It is common
in females and often occurs in immunocompromised patients. The lesion presents as
nodular and plaque-like lesions of the lower leg. Microscopic features
are of granulomatous perifolliculitis. The nodular granulomatous
lesions in the dermis contain individual dermatophyte hyphae.
Dermatopathology Quiz Case 20
Note the "sandwich sign" where the
hyphae are sandwiched at the interface between normal and abnormal layers
of cornified cells"
infection may display a wide range of microscopic features.
Changes in stratum
i) Presence of neutrophils;
ii) Compact orthokeratosis ;
iii) Presence of 'Sandwich Sign' -
Characterized by hyphae sandwiched
in between an upper normal basket weave stratum corneum and lower layer
of abnormal stratum corneum - (compact orthokeratotic or parakeratotic in
show: Mild spongiosis ; Prominent spongiotic vescicles (palms and
soles) ; Rarely subcorneal or intraepidermal pustules ; Chronic cases show
Dermis may show
sparse perivascular mixed inflammatory infiltrate or a heavy dermal
infiltrate with involvement of hair follicle.
Perifollicular neutrophils or a mixed inflammatory infiltrate may be present.
are identified in the tissue as branched, septate hyphae and spores.
usually stain with hematoxylin and eosin but are best demonstrated with
special stains for fungi.
arthroconidia invade the stratum corneum, hair follicle and hair shafts.
The pattern of hair invasion may be ectothrix, endothrix or endoectothrix.
rupture of a hair follicle and release of fungal elements into the dermis
elicits acute suppurative inflammation that eventually becomes
hyphae embedded in and surrounded by abundant Splendore - Hoeppli material
in the dermis and subcutaneous tissue may be misinterpretated by some
pathologists as grains and granules found in Mycetoma.
aggregates actually consist of clustered dermatophyte hyphae (pseudogranules)
each ensheathed by Splendore- Hoeppli material.
presence of hyphae in the very thin compactly orthokeratotic zone in the
lowermost part of the stratum corneum of a section stained by hematoxylin
and eosin is diagnostic of dermatophytosis.
Special stain for fungi:
Silver (GMS) ; Periodic Acid-Schiff (PAS) ; Gridley fungus ; GMS with
H&E counterstain (GMS/H&E).
Skin infections - (Histopathological