Is Fungal infection making your skin itchy ? A comprehensive synopsis

Itchy skin can be attributed to different etiological agents. Amongst those the most common is Dermatophytes which implies superficial fungal skin infection. These Dermatophytes belong to the genera Trichophyton, Epidermophyton and Microsporum. Interestingly, these three genera in order do not affect Skin, Hair & Nail respectively. Different terminologies have been coined to denote site specific involvement like Tinea Corporis( Torso), Tinea Capitis( Scalp), Tinea Cruris( Groin) , Tinea Pedis( Foot) , Tinea Mannum ( Fingers, Hand etc). The most consistent risk factor for Tinea remains poor personal hygiene, moisture due to excessive sweats, tight fitting garments , immune compromised state leading to altered host response like Diabetes Mellitus, Haematological Malignancy, patients receiving chemotherapy, DMARDs, immunomodulatory agents etc. 

Tinea spread through direct contact with infected humans or animals as well as contaminated fomites or vegetative matters. No age group is spared however there is a slight preponderance amongst post pubertal children and young adults probably due to physiological increase in sebum secretion secondary to androgen surge.

      It has been seen that most of the time clinical features of tinea e.g. maculopapular scaly erethamatous lesions with or without central clearing considerably overlap with other dermatological conditions and pose a challenge to clinch the diagnosis. The following chart illustrates the in & out of tinea corporis in an easy to understand format.

So here we go..

Tinea Corporis -

■Clinical Features 

Red scaly margin 

Papules & pustules

Mild prutitis

Asymmetrical lesions

■Clinical variants 

  ◇Kerion common in children and associated with scalp abscess

◇ Majocchi granuloma common in females around hair & hair follicles of legs

◇ Tinea incognito - Steroid modified tinea mainly found over trunks, limbs etc.

■Clinical Microbiology Lab Diagnosis : 

10% KOH for morphological identification of fungal etiology with seeding on SDA, PDA for culture confirmation with Fungal AST

Vitek 2 Compact can be employed for Fungal AST with MIC from pure culture growth from SDA/ PDA

■Differential Diagnosis of Tinea Corporis:

a) Discoid eczema ( nummular)

Less likely to have central clearing with more confluent scales 

b) Urticaria 

     Erethematous, pruritic with erethamatous wheal 

c) Contact Dermatitis

 

Well demarcated, erethematous lesion localised to the area of contact

d) Erethema marginatum

    

Flat erethamatous

e) Atopic Dermatitis 

Highly pruritic, lichenification in chronic lesions and also chronically relapsing

f) Plaque psoriasis

Annular , erethematous round or oval, pruritic plaques. Family History is positive. Nail pitting , arthritis , uveitis

g) Pityriasis rosea

Herald patch progressing to generalised rash 

h) Secondary syphillis 

Diffuse pattern, Symmetrical round or oval, pink -reddish macules 

i) Lichen Planus 

Pruritic papules/plaques

We hope to see you with another interesting Medical blog. Till then eat healthy, sleep well and see you soon !