Clinical and Biopsy Features of 31 Patients with Linear scleroderma of the scalp

Study of 27 Patients with En Coup de Sabre and 5 patients with Parry Romberg Syndrome

Scleroderma is a connective tissues disorder characterized by increased production of collagen. The term scleroderma is derived from the Greek word skleros (which means hard or indurated) and the word derma (which means skin). The work scleroderma is used to describe a disease characterized by progressive skin hardening and induration

It can be associated with systemic involvement in which case it is known as systemic scleroisis or it can be localized to the skin and underlying tissues in which case it is called localized scleroderma. Both localized and systemic forms are characterized by fibrosis of the skin.

Scleroderma is therefore typically divided into 2 forms. The first is “localized scleroderma” which includes circumscribed morphea, linear scleroderma, generalized morphea, pansclerotic morphea and mixed mophrea). The localized forms are confined to involvement of the skin and subcutaneous tissues. Localized scleroderma affects about 1 in 30,000 individuals. Caucasians are more affected than other racial backgrounds. Localized scleroderma tends to affect females more than males. The exception is linear scleroderma which affects males and females somewhat equally. Localized scleroderma affects both children and adults and the distribution is fairly similar.

The second is systemic sclerosis (systemic scleroderma) which involves the skin and internal organs. Systemic sclerosis is divided into limited cutaneous SSc, and diffuse cutaneous SSc. The limited form has mild to moderate, somewhat delayed organ fibrosis, and the diffuse cutaneous SSc form is associated with earlier and more severe organ damage.

Linear scleroderma

Linear scleroderma has three variants - a trunk/limb variant, a head variant (often called en coup to sabre) and the Parry Romberg syndrome.

Linear scleroderma is histologically similar to morphea but the lesions do not appear as patches but rather as linear bands. These bands can extent across a limb or part of a limb. in the case of LSCS they may extend across the scalp and face. .

Linear Scleroderma (LSCS)

When linear scleroderma involves the face or scalp, it is termed en coup de sabre. The term “en coup de sabre” was originally put forth by the French to depict the types of injuries inflicted soldiers who were struck on the head with a sword. The results of such injury was a thickened scar on one side of the forehead.

LCSC often beings with a hypopigmented or hyperpigmented streak on the forehead. That streak may become red and then indurated over time.

LSCS (en coup de sabre type) typically affects in children (67%), with a slight predominance in girls (about 2:1). It usually first appears in the first two decades of life. In a study from the Mayo clinic, the average age of onset was 13.6 years of age. In a study from Wisconsin, patients presented at 6.9 years of age (range 1-15 years).

Linear Scleroderma “en coup de sabre” is a linear localized form of morphea that typically affects the frontoparietal scalp and forehead. The skin may be hard and shiny and there is often overlying hair loss.

Coup de sabre lesions, particularly with craniofacial involvement, can sometimes be associated with neurologic abnormalities and seizures. Children with LSCS are often advised to undergo complete neurologic examination along with brain MRI as part of their evaluation.

Parry-Romberg syndrome (PRS)

Parry-Romberg syndrome is a condition associated with hemifacial atrophy of tissue below the forehead with little involvement of the skin. It is related to LSCS.

PRS was described first by Parry in 1825, then Romberg in 1846 and Eulenberg in 1871. It is a rare neurocutaneous syndrome characterized by progressive atrophy of tissues below the surface of the skin. The superficial skin is usually not involved or only mildly involved. It usually occurs on one side of the face and is also know by the name progressive hemifacial atrophy. PRS is felt to be an autoimmune disease and to be a type of variant of localized scleroderma.

In fact, PRS is felt to be a severe type of LSCS. Both conditions have associated seizures, dental and ocular abnormalities and both conditions have similar prevalence. It has been reported that PRS coexists in 20% to 37% of patients diagnosed with en coupe de sabre.

PRS has a female to male predilection of 3:2. Left side of the face is involved in more than 85% of cases - and affected areas overlies the buccinator and temporal muscles. It commonly affects the eyes and in about 15 % of cases is also associated with a variety of neurological disorders.

de Marsillac P et al. 2022

Authors set out to evaluate the epidemiological, clinical, trichoscopic, histopathological features and treatment of patients with linear scleroderma on the scalp. This study is of interest as it is one of the largest studies to address the clinical, epidemiological, trichoscopic, histopathological, and treatment findings of linear scleroderma of the scalp.

There were 31 patients in the study. 27 patients had the LSCS subtype and 5 had the PRS subtype. The mean age of patients was 32.1 years (with a range 7 to 69). Three quarters of patients (77.4%) were female. About one half were of skin phototype 2 (54.8%). Only 3.2 % of patients had a family history and that was limited to one patients with LSCS.

Alopecia was located in the frontal or fronto-parietal scalp in about 60 % of patients. The shape of the alopecic area was described as linear in 45.2 % and rounded in 35.5 %

Nearly all patients showed atrophy (96.8%) and many showed erythema (71%), dyschromia (54.8%), and 29.% had scaling.

Biopsies showed epidermal atrophy and loss of adnexal structures occurred in over 80% of the patients. Other features included perivascular lymphocytic infiltrate (72%), incontinence of pigment in dermis (55.6%), perifollicular fibrosis (38.9%). Interestingly, a perineural lymphocytic infiltrate was found in 56.3% of biopsies being more common in LCSC than PRS. Mucin deposition was seen in 50%

Treatment included high potency topical steroid (77.4%) followed by systemic steroids (48.4%) , topical tacrolimus (32.3%) and systemic immunosuppressants ( 100% treated with methotrexate). 40 % of those with PRS were treated with autologous fat grafting.

Comment.

This is an interesting study and one of the largest ones dedicated to linear scleroderma of the scalp. The study highlights the female predominance.

Furthermore, the study highlights an important histological finding - namely perineural lymphocytic inflammation being seen in 50 % of biopsies. This deserves further study and could help pathologists to differentiate challenging cases of linear scleroderma from lupus, dermatomyositis and lichen planopilaris. Early lesions can have overlapping features. The redness, scaling and dyschromia that is seen in LSCS can make the early diagnosis challenging in some cases.

REFERENCE

de Marsillac P et al. Clinical, epidemiological, trichoscopic and histopathological features of linear morphea on the scalp. J Eur Acad Dermatol Venereol. 2022 Jun 13. doi: 10.1111/jdv.18323. Online ahead of print.