Felted hair in rupoid psoriasis: a rare association.

Plica polonica is an acquired condition characterized by irreversible matting of hairs. It has been most commonly reported in association with psychiatric disorders. Here, we report a case of felting in rupoid psoriasis in a 13-year-old female.

INTRODUCTION

Plica polonica/plica neuropathica is a rare acquired condition of sudden onset characterized by irreversible entanglement of hair.[1] The term was coined by Le page in 1884, when he described a 17-year-old girl with a sudden onset of tangled scalp hair.[2] Simpson and Mullins subsequently reported instances of this disorder in association with various psychiatric disorders.[3] The condition is not uncommon and has been reported in various psychiatric disorders, parasitic infestations, vesico-bullous disorders, neglect of scalp hair and with the use of shampoos and hair lotions with cationic surfactants. To the best of our knowledge, it has not been described previously in association with rupoid psoriasis.

CASE REPORT

A 13-year-old female patient presented to our outpatient department with thick, scaly, cone-shaped lesions present over the trunk, back, upper, and lower extremities since 1 month. There was no history suggestive of any systemic or psychiatric illness. On examination multiple, discrete to confluent limpet-like, cone-shaped lesions were present on the above mentioned sites with erythema and slight scaling present over the face [Figure 1]. On the scalp, multiple plaques with asbestos like scaling were firmly adherent to the scalp and associated hairs [Figure 1]. All the finger and toe nails showed psoriatic nail changes. On clinico-pathological basis [Figure 2] diagnosis of rupoid psoriasis was made. All routine investigations were within the normal limits. She was started on 10 mg of methotrexate weekly and potent topical corticosteroid preparation over the affected sites, with significant clinical improvement of the cutaneous and scalp lesions, but with matting of hairs over the vertex of the scalp after 1 month, while patient was on the same treatment. History of vigorous rubbing of hairs was present. On examination, scalp had a matted, intertwined hair mass over the vertex and occipital region [Figure 1]. The hairs were strongly felted and could not be separated. The underlying scalp skin over the vertex and occipital region was normal, and there was no evidence of pediculosis or psoriatic lesions. Slight scaling was present on the frontal region of the scalp. Light microscopic examination of the involved hair revealed bending and twisting, but no hair shaft abnormality was present.

Figure 1

(a) Limpet-like scales of rupoid psoriasis present over the back. (b) Slight scaling and erythema over the face. (c) Thick psoriatic plaques over the scalp. (d) Felted hairs over the vertex and occiput

Figure 2

Histopathology showed psoriasiform epidermal hyperplasia, remarkable microabsesses in the horny layer with dense dermal edema and inflammatory infiltrate

DISCUSSION

Irreversible matting of scalp hair is rare but well described condition. In situations of gross neglect, it has been called plica polonica. In cases with hysterical illness it has been described as plica neuropathica.[4] Bogaty and Dunlap first used the term “matting of hair” in 1970 and compared the condition with “felting.”[5] Various physical factors have been attributed to the pathogenesis of plica [Table 1]. In our case, vigorous rubbing of hairs may have resulted in matting. Though various immunosupressants like azathioprine have been postulated as a cause for plica polonica, they caused hair shaft cuticle damage which was not seen in our case, ruling out methotrexate as a cause.[9]

Table 1

Physical factors attributed in pathogenesis of plica

Treatment of plica is difficult except for cutting the affected hairs. On one occasion, a patient separated the tangled hair using a knitting needle and olive oil as a lubricating agent.[10]