Postinflammatory hyperpigmentation in Adult
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Synopsis

Postinflammatory hyperpigmentation (PIH) describes localized darker skin areas as a consequence of trauma and/or inflammation. It can arise in all skin types but affects patients with darker skin phototypes with greater frequency and severity. There is no age or sex predilection.
The inflammatory process may be incited by an infection, allergy, drug reaction, mechanical or thermal injury, phototoxic eruption, or an intrinsic skin disease.
Although clinically benign, patches of PIH can cause significant cosmetic and psychosocial distress.
Inflammation may induce overproduction of melanin in the epidermis through the effect of inflammatory mediators such as metabolites of arachidonic acid and reactive oxygen species. PIH in the dermis results from damage to basal keratinocytes with release of melanin subsequently phagocytosed by dermal macrophages. Most lesions are a combination of epidermal and dermal pigmentation, the latter being more difficult to treat.
The lesions of PIH may be accentuated by sunlight.
The inflammatory process may be incited by an infection, allergy, drug reaction, mechanical or thermal injury, phototoxic eruption, or an intrinsic skin disease.
Although clinically benign, patches of PIH can cause significant cosmetic and psychosocial distress.
Inflammation may induce overproduction of melanin in the epidermis through the effect of inflammatory mediators such as metabolites of arachidonic acid and reactive oxygen species. PIH in the dermis results from damage to basal keratinocytes with release of melanin subsequently phagocytosed by dermal macrophages. Most lesions are a combination of epidermal and dermal pigmentation, the latter being more difficult to treat.
The lesions of PIH may be accentuated by sunlight.
Codes
ICD10CM:
L81.0 – Postinflammatory hyperpigmentation
SNOMEDCT:
238699007 – Post-inflammatory hyperpigmentation
L81.0 – Postinflammatory hyperpigmentation
SNOMEDCT:
238699007 – Post-inflammatory hyperpigmentation
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Differential Diagnosis & Pitfalls
Dermatologic conditions that can cause PIH:
Inflammatory skin conditions
PIH must be differentiated from other hyperpigmentation conditions, especially in cases where there is no history or a visible evidence of a preceding inflammatory process.
Inflammatory skin conditions
- Acne
- Atopic dermatitis and other eczematous eruptions
- Psoriasis
- Lichen planus
- Lichen planus pigmentosus
- Erythema dyschromicum perstans
- Pityriasis rosea
- Lichen simplex chronicus
- Systemic lupus erythematosus
- Sarcoidosis
- Dermatomyositis
- Immunobullous disorders (eg, pemphigus vulgaris, bullous pemphigoid)
- Scleroderma and morphea
- Phototoxic drug eruption (from minocycline, amiodarone, or chemotherapy)
- Fixed drug eruption
- Drug-induced flagellate pigmentation (from bleomycin)
- Erythema multiforme and Stevens-Johnson syndrome (from antibiotics, antiepileptic drugs, antituberculosis drugs, and NSAIDs)
- Minor abrasions and cuts
- Burns
- Friction
- Radiation (see radiation dermatitis)
- Dermabrasion
- Cryotherapy
- Lasers
- Intense pulsed light
- Chemical peels
- Microneedling
- Arthropod bite
- Papular urticaria
- Contact dermatitis
- Polymorphous light eruption
- Pigmented contact dermatitis (Riehl melanosis)
- Viral (eg, herpes simplex, herpes zoster, viral exanthems, molluscum contagiosum)
- Bacteria (eg, impetigo)
- Fungal (eg, dermatophytosis, pityriasis versicolor)
PIH must be differentiated from other hyperpigmentation conditions, especially in cases where there is no history or a visible evidence of a preceding inflammatory process.
- Melasma – commonly associated with hormonal changes in women (eg, pregnancy, oral contraceptive pills, perimenopause)
- Drug-induced hyperpigmentation – common drugs include antimalarials, amiodarone, chemotherapy drugs, heavy metals
- Addison disease due to adrenal insufficiency
- Acanthosis nigricans – commonly localized to knuckles, neck, axillae, and inner thighs; velvety appearance; related to insulin resistance and obesity
- Ultraviolet (UV)-induced tanning
- Exogenous ochronosis
- Periorbital hyperpigmentation
- Idiopathic eruptive macular hyperpigmentation
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References
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Last Reviewed:09/12/2019
Last Updated:11/05/2019
Last Updated:11/05/2019

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