Clawing to understand lichen nitidus
By Warren R. Heymann, MD
April 5, 2018
I enjoy diagnosing lichen nitidus (LN). Only dermatologists are aware of the entity, it is of little significance, and usually resolves on its own. Although the pathogenesis of LN is an enigma, the tiny, shiny, discrete papules (which may display the Koebner phenomenon), on the trunk, extremities, and genitalia are so characteristic, the diagnosis can be rendered with confidence at a glance.
That has always been the case for me — until I used my dermatoscope.
My first-year resident presented a case of a 27 year-old man with clinically classical genital LN. I have gotten into the habit of using my dermatoscope for looking at virtually any lesion — neoplastic or inflammatory — and am often bewildered by what I’m seeing. The patient’s dermatoscopic exam demonstrated uniform central (presumed) umbilications in each papule. My confidence regarding LN was shattered — was I really looking at molluscum mimicking LN? A biopsy confirmed that my clinical judgment was correct — it was LN. What I realized, though, is that I have not given LN much thought for the past few decades — it’s time for a refresher course!
The classical appearance of LN was described above, but there are multiple variants. Generalized (1), mucosal/tongue (2), palmoplantar (3), eyelid (4), Blaschkolinear (5), hyperkeratotic/hypertrophic (6), and perforating types have been reported (7).
Nail changes have been rarely described in LN, which may precede the cutaneous presentation; they may be associated with subtle lichenoid papules on the affected digits. Pits, trachyonychia, longitudinal ridges, transverse ridges, and median canaliform dystrophy have been described. In contrast to lichen planus, nail changes in LN are less severe, with no pterygium formation or anonychia. Presumably, these changes are secondary to nail matrix involvement. (8)
Histological changes are pathognomonic of LN characterized by a “ball and claw” appearance of rete ridges clutching a lymphohistiocytic infiltrate. The epidermis overlying the infiltrate is of atrophic, displaying vacuolar alteration with Civatte body formation. (7). A similar dermatoscopic description to my patient was detailed in the case of a 30 year-old man with umbilicated lesions on his hands. (9) My patient’s lesions were not clinically umbilicated — I presume the dermatoscopic changes observed were secondary to the central epidermal changes noted histologically — there was no histologic evidence of perforation.
The etiology of LN is unknown. Rare familial cases have been reported. There has been speculation of some association with Crohn disease and Down syndrome (1). Generalized LN has now been reported due to anti-PD-1 therapy, as in the case of a 40+ year-old man with metastatic lung carcinoma treated with nivolumab. His lesions responded to topical betamethasone (and untreated sites evolved resemble lichen planus). (10). As previously discussed in DI&I (“Thinking of discontinuing a PD-1 inhibitor because of a lichenoid eruption? Don’t do it!” May 21, 2016), there is no need to discontinue PD-1 inhibitors for lichenoid eruptions.
Therapeutically, you’ll look like a savant, because no matter what you prescribe (steroids, calcineurin inhibitors, retinoids [acetretin], phototherapy, etc.), most cases of LN will spontaneously regress. (1)
Nearly 40 years ago, I was probably just like my first year resident, justifiably feeling good about diagnosing LN. Retrospectively, it’s humbling to think that I really do not understand LN any better now than I did then.
Point to remember: There are many clinical variants of lichen nitidus — when using the dermatoscope, the epidermal changes may allow for an umbilicated appearance.
1. Synalkielwicz J, et al. Generalized lichen nitidus: A case report and review of the literature. Postepy Dermatol Alergol. 2016; 33(6): 488-490.
2. Costa de Araujo P, Lechien JR. Lichen nitidus on the dorsal tongue. Ear Nose Throat J. 2016; 95:143.
3. Qian G, et al. Different dermoscopic patterns of palmoplantar and nonpalmoplantar lichen nitidus. J Am Acad Dermatol 2015; 73: e101-3.
4. Liu ET, et al. Lichen nitidus of the eyelids. Ophthal Plast Reconstr Surg. 2017; 33:e85-e86.
5. Aravind M, et al. Blaschkolinear acquired inflammatory skin eruption, or blaschkitis, with features of lichen nitidus. JAAD Case Rep 2016; 2: 102-4.
6. Ho JD, et al. Hyperkeratotic and hypertrophic lichen nitidus. Dermatol Online J 2017; 23: 15.
7. Zussman J, Smart CN. Perforating LN. Am J Dermatopathol 2015; 37: 406-8.
8. Tay EY, et al. Lichen nitidus presenting with nail changes – Case report and review of the literature. Pediatr Dermatol 2015; 32: 386-8.
9. Matinez-Mera C, et al. Dermoscopy of a perforating lichen nitidus. Australas J Dermatol 2018; 59: 61-2.
10.Cho M, et al. Generalized lichen nitidus following anti-PD-1 antibody treatment. JAMA Dermatol 2018; 154: 367-9.
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