Correspondence Address:
Pragya Ashok Nair
Department of Dermatology, Pramukhswami Medical College, Shree Krishna Hospital, Karamsad, Anand - 388 325, Gujarat
India

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Sir,

A 32-year-old male, born to nonconsanguineous marriage, presented in the outpatient department with a chief complaint of scanty hair since birth. The patient gave a history that his hairs did not grow up to the length which required haircut. There was no history of any seasonal variation and trauma to hair. No history of topical application, food/drug allergy, fever, retarded growth, juvenile cataract, chest pain, abdominal pain, or vomiting was present. He was a known case of chronic pancreatitis and diabetes mellitus on medication. History of multiple stones in gallbladder 2 years back was present, for which gallbladder was removed. Positive family history of diabetes mellitus and sparse hair in father [Figure 1], sister, and grandmother was present. Pedigree chart of family members suffering from similar condition is shown in [Chart 1]. Cutaneous examination showed diffuse light brown to black, sparse hair with pustules and keratotic papules over the scalp [Figure 2]. Hair over eyebrows and eyelashes and axillary, pubic, or body hair were normal. Nail and teeth were normal. Trichoscopy done with Illuco dermoscope, model-1100, ×10 magnification in cross-polarized light illumination, showed hair shaft with uniform elliptical nodes, intermitted constrictions, broken hair, and perifollicular scaling [Figure 3]a and [Figure 3]b. Biopsy was not done as the patient did not consented for it. The history, cutaneous examination, and trichoscopy suggest the diagnosis of monilethrix.{Figure 1}{Figure 2}{Figure 3}[INLINE:1]

The word monilethrix is derived from Latin “monile” meaning “necklace” and the Greek “thrix” meaning “hair.”^[1] It is a rare hereditary hair shaft defect with variable expressivity characterized by the presence of beaded or spindle-shaped shafts of the scalp hair and manifest as congenital hypotrichosis.^[2]

Monilethrix is predominantly an autosomal dominant disease with regular thinning of hair shaft at constricted points. However, few cases of autosomal recessive inheritance are also reported. Several genetic studies have suggested that the gene responsible for this disorder has been mapped to chromosome 12p13 and involves type II cortex keratin genes hHb6 and hHb1. Autosomal dominant monilethrix is caused by mutations in hair keratin genes KRT81, KRT83, or KRT86, whereas in autosomal recessive form, mutations in the desmoglein-4 gene have been reported.^[3]

Hairs are usually normal at birth but are progressively replaced by abnormal hair during first few months of life. Patients have short and fragile hair usually growing up to 1–2 cm long, not requiring haircut since childhood over the occipital and temporal scalp.^[1] Clinically, it presents with extremely short, fragile hair as broken stubs emerging from keratotic follicular papules, especially in the occipital region but occasionally eyelashes, eyebrows, axillary, pubic, and limb hair are also affected. The increased fragility of the hair shaft to premature weathering results in its inability to attain a normal length. It is associated with trichorrhexis nodosa, nail and teeth defects, retarded growth, and juvenile cataracts.

Diagnosis of hair shaft disorders is typically based on scanning electromicroscopy and light microscopy which shows uniform nodosities with intermittent constrictions at which there is shaft breakage. This is called “regularly bent ribbon sign.”

Trichoscopy as a noninvasive technique can be used as a rapid diagnostic tool for monilethrix, which shows hair shafts having regular variations in the diameter with elliptical dilated uniform spindle-shaped nodes and intermittent constrictions (internodes) with hairs bent at multiple locations in a regular fashion. There is a tendency to shaft fracture at the sites of constrictions.^[2]

Fusiform nodes are microscopically seen at every 0.7–1 mm. Among the nodes, there is usually no hair marrow (medulla).^[4] These unmedullated internodes are the sites of hair breakage, leading to dystrophic alopecia. Perifollicular scaling and keratotic plugs may be seen on dry dermoscopy.^[5] Our case also showed perifollicular scale like in case of two male siblings aging 24 and 21 years reported by Jain and Khopkar^[6] This case report highlighted patterned distribution of hair loss in monilethrix probably due to the early unmasking of androgenetic alopecia and the use of trichoscopy as the diagnostic modality. Patients with monilethrix show improvement in hair growth after puberty, which is in contrast to our case, where the patient had sparse and fragile hair.

There is still no definitive treatment. Avoiding trauma is the primary goal in managing this condition. Various activities which cause an increased susceptibility to fracture of the hair shafts including dyeing, bleaching, curling, etc., should be avoided. Karincaoglu et al. described a very good clinical and cosmetic result with oral acitretin in a 7-year-old girl.^[7] However, recurrence was observed. A therapeutic trial with oral N-acetyl cysteine was also attempted, with varied response.^[8] Treatment modalities such as griseofulvin, iron supplementation oral retinoids, topical 2% minoxidil, etc., have shown improvement in isolated cases.

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Conflicts of interest

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