What Is Zosteriform Lichen Planus?
Zosteriform lichen planus is a type of cutaneous lichen planus that can arise from a healed episode of herpes zoster or develop independently without any prior history of varicella-zoster virus infection or herpes zoster. Lichen planus is an autoimmune disorder of the skin and mucous membranes. However, its exact etiology is still unknown. The lesion comprises flat-topped, itchy, polygonal papules that aggregate to form a plaque. A dermatological sign includes huge, distinct, band-like, hyperpigmented, papular patches that follow Blaschko's lines.
What Is the Prevalence?
Lichen planus is an inflammatory condition of the skin and mucous membranes that develops without any known etiology. The typical age of onset is 50 years old, and middle-aged people are most frequently affected. There is no racial predilection, and the occurrence is equally dispersed worldwide. Females are more susceptible than males. Mucous membranes are affected in approximately 65 percent of cases. Oral LP patients have Wickham's striae, a lacy white reticulation on the buccal mucosa that may progress to squamous cell carcinoma in 0.2 percent of cases annually. The nails may be impacted simultaneously with the scalp, resulting in scarring alopecia.
What Are the Causes of Zosteriform Lichen Planus?
Zosteriform lichen planus may be associated with specific drugs and disorders, such as hepatitis C. Still, the cause is unknown and is assumed to be a T-cell-mediated immunological response. There are around 20 variations in addition to the traditional appearance, which are grouped according to the morphology and arrangement of the lesions. Many unusual manifestations of LP, including actinic, hypertrophic, vesiculobullous, and linear, have been reported. LP mostly affects the skin and mucous membranes, but the cytotoxic T lymphocytes attack and kill the keratinocytes and melanocytes that make up the basal layer of the epidermis. The breaking down of the melanocytes results in the release of melanin pigment, which causes the skin to become hyperpigmented.
What Are the Signs of Zosteriform Lichen Planus?
Zosteriform lichen planus is defined clinically by flat-topped, violaceous, pruritic papules or plaques. Zosteriform LP is usually symmetric in appearance, and the eruption preferentially affects the flexure surfaces of the extremities. Zosteriform lichen planus does not have a distinct dermatomal distribution. Instead, it follows Blaschko's lines, which depict embryonic cell migration. However, Blaschko's lines do not correspond to the underlying structures, such as nerves, soft tissues, and muscles. Blaschko's lines exhibit distinct superficial patterns on the following body parts: the breast area to the upper arm (inverted U-shaped), the upper back (V-shaped), the belly (S-shaped), and the front and rear of the lower extremities (perpendicular to the above forms). The illness does not prevent the patient from engaging in regular activities, but it is recommended that the patient refrain from causing any skin trauma. The illness typically exhibits an isomorphic response (Koebner phenomenon).
The development of a linear pattern consequent to trauma, characterized by narrow lines smaller than 2 cm in diameter that follow the path of the vein or lymph channel, is caused by Koebnerization, which can be observed in linear LP. Zosteriform LP is distributed in a band-like pattern made up of broader lines with a diameter of more than two cm. They can be distinguished immunohistochemically by the presence of varicella-zoster antigens in the zosteriform LP lesion. These antigens are absent from linear LP.
Recent research suggests that rather than following a dermatome, the lesions in zosteriform LP follow the lines of Blaschko. Blaschko's lines are imperceptible skin lines that are thought to show the migration of embryonic cells. However, some people still think that lesions are associated with cured herpes zoster. The differential diagnoses include inflammatory linear verrucous epidermal nevus, linear psoriasis, lichen striatus, and linear epidermal nevus.
What Is Histopathology of Zosteriform Lichen Planus?
Histopathologic analysis reveals a band-like lymphocyte infiltrate at the dermal-epidermal junction, distinguishing Zosteriform LP. Other prominent features are hyperkeratosis, basal layer vacuolar degeneration, wedge-shaped hypergranulosis, and rete ridges with sawtooths. Civatte bodies, also known as colloid or cytoid bodies, are found in the papillary dermis as well as in the interface between the dermis and epidermis. Lichen planus exhibits cytoid structures, shaggy fibrin, and IgM immunoglobulin deposition at the dermo-epidermal interface on direct immunofluorescence (DIF). This helps differentiate LP from hypertrophic lupus erythematosus, which is identified by a continuous band of IgG, IgA, IgM, and C3 at the dermo-epidermal junction on direct immunofluorescence.
What Is the Treatment of Zosteriform Lichen Planus?
There is no permanent cure for lichen planus, and the condition is self-limiting. Different therapeutic techniques are available to induce remission and relieve associated pruritus. Topical and systemic medicines may be used to treat the condition. Pruritus can be relieved by using oral antihistamines like Hydroxyzine and Diphenhydramine. Other options include topical antipruritics such as Doxepin, Pramoxine, camphor, or menthol. Administering topical steroids at a high dosage twice daily is the first-line treatment for cutaneous lesions. Systemic corticosteroids might be administered as a second-line treatment for more severe illnesses.
Alternative therapies include immunosuppressive medications such as Cyclosporine, Methotrexate, Azathioprine, Dapsone, Retinoids, and topical Tacrolimus. Adjuvant therapies include psoralen with ultraviolet A (PUVA) and narrow-band UVB phototherapy. More recent LP therapy approaches, including oral Metronidazole and Enoxaparin sodium, have also been successful. Corticosteroids are the primary treatment option for oral LP because they suppress cell-mediated immune response. These may be administered systemically, intralesionally, or topically. It is quite effective to use topical and systemic steroids simultaneously. Generalized oral lesions can be treated with a steroid mouthwash twice a day.
Conclusion:
The therapeutic approach for all forms of LP is the same, even if zosteriform LP is a rare variation with a distinctive skin distribution. Histopathological findings help support the clinical diagnosis. The differentiation among various linear dermatoses is essential for effective therapy.
