A Case of Localized Scalp Psoriasis Triggered by Microsporum canis Infected Tinea Capitis and Review of Published Literatures

Abstract

A 5-year-old girl presented at our clinic with 2-month history of breakage of hair associated with white scaly patches with sizes of the palm on the scalp (Figure 1). She was diagnosed as tinea capitis at the local hospital and was treated with oral terbinafine 125 mg for 18 days and the lesion completely healed. A month after discontinuing medicine, her condition exacerbated then she continued to take oral terbinafine, but the lesion enlarged gradually. A palm size erythema with white scales with broken hair was noticed and she felt intense itch.Circular and oval tiny spores outside of hairs were observed by direct examination with 15% KOH smear of scales from the scalp (Figure 2A). Fungal culture of scales revealed light yellow filamentous colonies ( Figure 2B) and microscopic examination of a slide culture showed large separated spindle-shaped spores ( Figure 2C), which was consistent with the features of Microosporum canis. Genomic DNA was extracted using a DNA kit (Omega bio-tek, USA) and amplification of the intergenic transcribed spacer (ITS) regions flanking the 5.8S region of the rDNA was performed by PCR. The samples were subsequently sent to Invitrogen Life Technologies for DNA purification and bidirectional sequencing. A BLAST search in GenBank using the ITS sequence showed 99% homology to Arthroderma otae (the teleomorph of M. canis). The sequence has been submitted to the gene data bank and registered under the accession number of KF733019. The patient was diagnosed with tinea capitis caused by M. canis and treated with oral itraconazole 100mg and local application of naftifine and ketoconazole cream once a day for nearly 2 months, but the lesion did not heal completely, AbstractWe report a case in which patient was initially ill with tinea capitis infected by Microsporum canis later triggered the local scalp psoriasis. Tinea infections always confused with psoriasis, a review of published studies revealed 14 cases of fungal confused with psoriasis.Keywords: Scalp; Lesion; Psoriasis; Spores white scaly patches was also observed on the scalp ( Figure 1B) but direct microscope examination and culture both negative. We carefully interviewed her family history, her mother and maternal grandfather had a history of psoriasis. She was advised for tissue biopsy which showed hyperkeratosis and parakeratosis, acanthosis with elongation of the epidermal rate ridges (Figure 3), indicated the pathology of psoriasis. Periodic acid-Schiff (PAS) and silver staining were both negative. After topical application of 0.03% tacrolimus, the patient was cured ( Figure 1C) after 14 days. DiscussionPsoriasis is a chronic disease of skin, with prevalence of 2-3% in the general population [1]. Several factors have been identified as being associated either with causation of psoriasis or with triggering exacerbations or remissions, including genetic determinants, racial and regional variation, injury and infection, cigarette smoking, alcohol, diet and other diseases [2]. In our case, first time the patient was diagnosed as t...