Bilateral Onychodystrophy in a Boy With a History of Isolated Lichen Striatus

Many of the reported cases of LS have described a pattern of distribution along the lines of Blaschko.^5,6,16,17 Lines of Blaschko are thought to be embryologic in origin and caused by the segmental growth of clones of cutaneous cells or the mutation-induced mosaicism of cutaneous cells, which led to the theory that mosaicism is involved in LS. Lichen striatus needs to be differentiated from other conditions with similar cutaneous appearances (eg, lichen nitidus, linear lichen planus of the digits, linear psoriasis, linear keratosis follicularis, linear epidermal nevus).

Skin biopsy to confirm the diagnosis rarely is necessary, as LS is a self-limited disorder and generally no treatment is recommended. Topical and intralesional steroids do not routinely impact the resolution of LS; however, emollients and topical steroids may be used to treat associated dryness and pruritus, if present.¹⁸ Immunomodulators such as tacrolimus and pimecrolimus have been successfully used in treating persistent and pruritic LS lesions on the face and extremities.^19,20 Tacrolimus also has been successfully used to treat nail abnormalities in LS.²¹

Guardians and family members should be reassured that LS is a benign condition that generally resolves spontaneously within 3 to 12 months. Also, guardians should be counseled regarding the possibility of postinflammatory hyperpigmentation or hypopigmentation, which may last for several months to years, particularly in children with darker skin types. Lichen striatus of the nails may have a more protracted course, lasting from 6 months to 5 years,²² but usually resolves spontaneously and without deformity.

Our patient developed a rare case of isolated LS at 2 years of age. Reports have suggested later onset of the condition, with more than 50% of all LS cases occurring in children aged 5 to 15 years.^1,2 Despite the earlier onset in our case, the patient still presented with the classic nonpruritic single linear band of papules that is characteristic of LS.

The nail involvement in our case is quite intriguing because of its rarity, timing, and extent of involvement. Nail involvement is generally uncommon in LS, with approximately 30 cases reported worldwide since 1941.⁷ The nail changes in our patient were unique in their timing, with the isolated onychodystrophy developing 3 years after the initial skin lesion. This subtle timing may pose a diagnostic challenge in patients with LS if treating physicians are unable to link the presenting onychodystrophy to the earlier cutaneous component of the condition. Two reports have shown that nail changes in association with LS may occur at any time before, after, or concurrently with the skin lesions,^4,8 suggesting that on rare occasions, as in our case, nail involvement may be the only area of involvement without the presence of typical LS skin lesions.⁸

The nail involvement in our patient also showed a greater severity than prior reports,^8,9 as he lost 2 fingernails completely before regrowth. Also, the bilateral distribution of onychodystrophy in our patient involving both the fingernails and toenails appeared to be consistent with a report by Al-Niaimi and Cox.²²

Nail involvement in cases of LS may be underreported when, as in our case, nail dystrophy presents as the only area of involvement without the presence of the typical skin lesions characteristic of LS. It is reasonable to recommend that clinicians facing similar presentations of isolated onychodystrophy should include the possibility of LS in the differential diagnosis before committing patients to a more common diagnosis (eg, onychomycosis). Clinicians should inquire about any history of cutaneous LS and counsel patients to return for treatment should skin lesions develop that are suggestive of LS.