Confluent and reticulated papillomatosis L83.x

Sporadic, rarely familial disease similar to acanthosis nigricans or combined with acanthosis nigricans with persistent, brownish or brownish-yellowish smaller or larger patches or brown, slightly hyperkeratotic (not granular hyperkeratotic but rather velvety hyperkeratotic) reticulated papules and plaques. Often also regarded as a clinical variant of pityriasis versicolor, especially if it has not been treated for a long time. Sometimes the clinical picture also presents in the context of mild ichthyosis. To differentiate it from other hyperpigmentations, it can be checked whether the plaques can be washed off with soap and water, in which case it is dermatosis neglecta, or whether the plaques can only be removed with alcohol, in which case it is terra firma-form dermatosis (TFFD).

m:w=1.4:1.0 (Negris OR et al.2024)

Unexplained.

Genetically determined (familial occurrence has been described) disorders of keratinization with association to acanthosis nigricans(pseudoacanthosis nigricans) have been discussed. Amyloid deposition and a loss-of-function mutation in keratin 16 have also been discussed (Lim JH et al. 2016)

Reactive epidermal proliferation caused by Malassezia spp. (DD: atypical pityriasis versicolor) or gram-positive bacteria (Dietziaceae spp. from the Actinomycetales order) have also been described

Associations with diabetes mellitus (insulin resistance?), obesity and hormonal disorders (thyroid dysfunction) are possible. The occurrence of confluent and reticular papillomatosis has been described in connection with a spindle-inhibiting and alkylating chemotherapeutic agent (paclitaxel, carboplatin /Negris OR et al. 2024)

Gynecotropia is being discussed (?) ! Age of manifestation: 10-36 years of age (average age in smaller studies is 19 years). Frequency peaks shortly after puberty. Dark-skinned people are affected twice as often as light-skinned people (this statement is disputed by others/Negris OR et al. 2024).

Mainly sternoepigastric area, intermammary region, also spreading over abdomen, neck, shoulder, back. Face remains free. Less frequently also in the genital area.

Chronic persistent (duration of the disease before diagnosis about 3 years) skin disease with multiple, flat, gray to brown, up to 0.5 cm large, blurred, slightly scaly, velvety papules, which can confluent to larger (up to 10 cm), flat homogeneous plaques, but can also form reticular or striped patterns and can confluent to dirty brown areas in the intertriginous areas.

Criteria varies according to Davies:

• velvety, brown-yellow or brownish papules and plaques
• filled flat plaques or net-like patterns
• seborrhoic zones
• proximal trunk, neck, also genital region
• chronic course
• negative fungus detection
• no therapeutic success with antimycotics
• no itching
• Good response to minocycline/doxycycline
• Histology not very specific.

Acanthosis nigricans benigna; Pseudoacanthosis nigricans; Pseudoatrophoderma colli; Pityriasis versicolor, M. Galli-Galli.

Mild keratolytic measures with urea-containing external agents, e.g. a 5-10% anionic urea cream R102 or emulsion R104.

If pityrosporon species are detected, supplementary antimycotic therapy with a solution containing clotrimazole(e.g. Canesten solution, Cutistad, R055 ) or an antimycotic cream, e.g. ketoconazole cream(e.g. Nizoral) or bifonazole cream(e.g. Mycospor).

Good therapeutic success is achieved with Minocycline 2 times/day 50-100 mg p.o. (complete healing in 6-8 weeks/75% of cases) or Doxycyclin 2x/day 100mg p.o.

Therapy duration 6-8 weeks. Recurrences after discontinuation are possible.

Alternatively, a systemic therapy with acitretin or isotretinoin can be applied.

It is to be assumed that the clinical picture of the "confluent and reticular papillomatosis" described by Gougerot and Carteaud does not conceal an etiopathogenetically uniform clinical picture. Rather microbial factors, a tendency to obesity, genetic factors like dark-skinnedness seem to lead to this mild cornification anomaly.

16-year-old obese female patient with non-pruritic HV on décolleté and neck since 2 years. Findings: Reticular, also striated, in places confluent to larger plaques, gray-brown papules, in places verrucous.

Histology: Discrete lymphocytic, superficial, interstitial dermatitis with papillomatosis and orthohyperkeratosis. Masses of bacteria in the stratum corneum. No mycelia or spores.

Mycology (native specimen): Neg.

Bacteriology: Staph. aureus, minocycline sensitive.

Laboratory: Inconspicuous.

Therapy: Frustrating external (keratolytic) therapy with urea, benzoyl peroxide and glucocorticoids at first. Internal therapy with minocycline (2 times/day 50 mg p.o.) for 6 weeks complete healing of all HV.

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