Lichen amyloidosis E85.4

Freudenthal, W 1930

Primary cutaneous amyloidosis (keratinamyloidosis) with dense papules and very intense lesional pruritus. Recently, some authors understand itching as the primary stimulus of amyloid deposition, which is reactively followed by the described skin changes with subepidermal deposition of amyloid (due to the traumatic permanent damage caused by scratching). See also amyloidosis.

Common in Asians and Africans. Also in Caucasians, but rather rare.

Unknown.

Familiar occurrence.

Principle: Apoptotic keratinocytes (this apoptotic process is a normal degradation process in the skin) convert their alpha helix into a beta leaflet structure from unexplained reasons. As a result, these keratin structures can no longer be phagocitated by macrophages. As it were, they remain in the dermis as clumsy, non-degradable ("keratinamyloid" or amyloid K) organic material. This process is not reversible.

m:w=3:2; usually higher age.

Extremities extensor sides, especially lower legs (86% of cases)

less frequently arms (10%) and

Back

Permanent, strong to excessive, lesional itching(pruritus = leading symptom)

Very hard, skin-colored to brown, usually grouped, warty-rough, or also lichenoid shiny, 0.2-0.4 cm large, in places excoriated, nodules with tendency to confluence, so that 3.0-5.0 cm large 0or larger hard plaques with pelted or verrucous surface develop.

A special form is biphasic cutaneous amyloidosis, in which papular and patchy skin lesions occur simultaneously.

Symptoms of lichen amyloidosus persisted for 6-20 months prior to diagnosis in larger studies.

Homogeneous eosinophilic plaques in the papilla tips, acanthosis, hyperkeratosis, hypergranulosis; lateral displacement of the reticulum cones. Traces of amyloid are often also found in the reticular dermis. The amyloid can be detected with crystal violet staining (metachromasia) or Congo red staining (green glow in polarized light). Immunohistological detection of cytokeratin positive keratin filaments (!).

Lichen simplex chronicus

Lichen planus

Lichen planus verrucosus

Prurigo nodularis

Keratosis pilaris

Improvement of symptoms by external glucocorticoids, e.g. 0.1% betamethasone(e.g. Betagalen, Betnesol) triamcinolone(e.g. Triamgalen, R259 ) or 0.05% clobetasol ointment or cream (e.g. Dermoxin, R054 ) under occlusion for several hours. Clinical improvement over several days to weeks.

For smaller foci, glucocorticoids intralesionally such as triamcinolone acetonide crystal suspension(e.g., Volon A, 10-40 mg together with 3-5 ml lidocaine or mepivacaine draw up and apply intradermally! in a fan shape).

In case of extensive foci, e.g. on the back, dermabrasio or laser therapy,_{CO2 laser} or erbium laser may be recommended. Theoretical principle: elimination of amyloid, which cannot be degraded by the organism, by the abrasive effect with the consecutive exudative inflammatory reaction. Therapeutic effects (no itching) for months to years.

Good effects are reported from local therapy with 50% dimethyl sulfoxide solution(DMSO) R079 (1 time/day for several months). Under this therapy, marked improvement of itching; regression of lichenoid papules within 8-12 weeks.

Single observations reported good effects of tacrolimus.

Acitretin (Neotigason) initially 0.5 mg/kg bw, continuous therapy with 0.1-0.2 mg/kg bw tentatively as monotherapy or in combination with one of the surgical procedures (not very successful in our own experience).

In severe cases with pronounced pruritus, cyclophosphamide (Endoxan) 50 mg/day may be tried as continuous therapy.

Of note is the observation that families with multiple endocrine neoplasia type 2A (= Sipple syndrome [MEN type 2A]) and familial medullary thyroid carcinoma (FMTC) with activating mutations in the RET oncogene have a higher incidence of lichen amyloidous.

Furthermore, associations between lichen amyloidous and Kimura disease have been described (Teraki Y et al. 2002; Shankar S et al. 2004). In one case, treatment with cyclosporine dramatically improved both Kimura disease and lichen amyloidosus lesions. Although Kimura disease and lichen amyloidosus are both rare, distinct entities, approximately 20 cases have been described to date in which Kimura disease and lichen amyloidosus occurred together.

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