Lichen planus pigmentosus (LPP) is an uncommon variant of lichen planus. The association of lichen, lupus and Hashimoto’s disease has rarely been reported [1]. We report the case of a patient with simultaneous lichen planus pigmentosa and Hashimoto’s thyroiditis.

R.A, female, age: 60, presenting with Hashimoto’s thyroiditis since 2016. Systemic lupus erythematosus since 2019 with skin, joint and renal involvement of type V lupus nephropathy. On examination: she presented with reticulated hyperpigmentation on the malar, frontal and perioral areas against a background of erythema (Fig. 1), hyperpigmentation and Wickham striae on the lips. Dermoscopic examination: brown background, vascular structure, perivascular pigment deposition. Cutaneous biopsy is consistent with reticular lichen planus pigmentosa.

Figure 1: Reticular hyperpigmentation.

The association of lichen planus pigmentosus with other autoimmune processes raises the possibility that patients with LPP may in fact develop an autoimmune status that predisposes them to auto-aggression against different targets [2]. A study of the association between oral lichen planus and Hashimoto’s thyroiditis in 245 patients showed that 46% of women with oral lichen planus had Hashimoto’s thyroiditis. However, no studies have been carried out on the association between lichen planus pigmentosa and Hashimoto’s thyroiditis [3]. Cutaneous lupus erythematosus and lichen planus pigmentosus are considered to be photo-aggravated dermatoses, but there are no studies on the association of the two or on causality.

However, the particularity of our patient is the association of three autoimmune pathologies, which raises the question whether one autoimmune disease leads to another.

REFERENCES

1.Bastos Gomes AC, Bimbi C, Brzezinski P. Lichen planus pigmentosus inversus associated with oral lichen planus. Our Dermatol Online. 2020;11:156-7.

2.Youssef M, Lahouel I, Korbi M, Soua Y, Marmouch H, Akkari H, et al. Lichen planus pigmentosus and association with autoimmune diseases:A case–control study. Our Dermatol Online. 2019;10:125-30.

3.Thokchom N, Verma K, Hafi BNA, Kshetrimayum S, Hmar V, Kongbam L, et al. A study on the association between thyroid dysfunction and various dermatoses in northeastern India. Our Dermatol Online. 2022;13:143-7.