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Lower Leg Dermatitis

Essentials

  • Skin problems of the lower legs are common.
  • Stasis dermatitis and asteatotic eczema are detected clinically.
  • In patients with leg ulcers, contact allergy to topical agents may develop.

Investigations

Common types of dermatitis encountered in the lower legs

Stasis dermatitis and venous leg ulcer

  • See also the article Venous insufficiency of the lower limbs Venous Insufficiency of the Lower Limbs.
  • The patient usually exhibits clinical signs of venous insufficiency (hyperpigmentation, dermatoliposclerosis, visible varicous veins) (picture 1).
  • Typically occurs as cutaneous pigmentation (pictures 2 3) around leg ulcers.
  • The cornerstones of treatment include compression therapy and moderately potent to potent glucocorticoid creams.
  • Whenever possible the underlying venous insufficiency should be surgically corrected Venous Insufficiency of the Lower Limbs.
  • Patients may develop contact allergy to topical agents.

Asteatotic eczema

  • Often seen in elderly individuals, caused by skin dryness and excessive washing (soap, abrasive brushes, sauna).
  • The skin dries particularly in the winter, and the use of basic topical ointments as well as moderately potent to potent glucocorticoid creams is indicated.
  • The condition usually improves spontaneously in the summer.

Atopic dermatitis

  • It is possible for atopic dermatitis to occur on the legs, but it usually is also present in other typical skin areas.
  • The key to correct diagnosis lies within the patient's history.

Nummular dermatitis

  • See Nummular Dermatitis.
  • The most common areas involved are the extensor aspects of the extremities and the back. Occurs typically on the legs and often also on the arms as itchy, round and scaly patches (picture 4).
  • May worsen during winters and because of the skin becoming dry.
  • Successful management requires the use of a potent glucocorticoid cream for an adequately long time (2-4 weeks).

Psoriasis

  • See Psoriasis.
  • Frequently seen on the lower legs and particularly around the knees.
  • In most cases, the patient will also have psoriasis on other skin areas.
  • Psoriasis on the legs is treated following the same principles as used in psoriasis affecting other skin areas.

Tinea

  • See Dermatomycoses.
  • Tinea can sometimes affect the lower legs, in which case it usually is also found on the feet.
  • Fungal samples will confirm diagnosis.

Allergic contact dermatitis

Neurodermatitis (lichen simplex chronicus)

  • Neurodermatitis may appear without a distinct preceding cause, but often it is a complication of an existing itchy rash, e.g. atopic dermatitis.
  • The condition is characterised by a cycle of itching and scratching, which may become chronic and recur easily.
  • The ankle and lower leg are typical sites for neurodermatitis (pictures 6 7).
  • Potent to super potent glucocorticoids are required for treatment.
  • Occlusive dressings have also been used.
  • Group III glucocorticoid cream or solution is spread over the rash, which is then covered with a hydrocolloid dressing (e.g. Duoderm® ). The occlusive dressing is changed every 2-4 days 2-3 times.

Prurigo nodularis

  • Prurigo nodularis is considered to be a widespread version of neurodermatitis.
  • The condition is based on a cycle of itching and scratching and often becomes chronic.
  • Raised nodules of 0.5-1 cm in diameter, often with a crusted top, develop on the pruritic site secondary to scratching and picking at the skin (picture 8).
  • Pruritic nodules most commonly occur on the limbs (e.g. on the legs) and the trunk.
  • The most common treatment modalities include potent glucocorticoid creams, a course of systemic glucocorticoids, sedating antihistamines, doxepin 10-25 mg once or twice daily, mirtazapine at night 7.5-15 mg once daily, amitriptyline 10-25 mg once or twice daily etc. as well as light therapies.

Lichen planus

  • The sites of predilection for lichen planus Lichen Planus, in addition to the wrists, are the ankles and legs (picture 9).
  • Chronic hypertrophic lichen planus almost invariably occurs on the legs and greatly resembles prurigo nodularis (picture 10).

Erysipelas and cellulitis

  • Rapid onset, high fever and unilateral well-demarcated, tender erythema and oedema (pictures 11 12) are typical of erysipelas Erysipelas.

Pigmented purpuric dermatosis (purpura pigmentosa)

  • The aetiology is unknown, but the most common site for pigmented purpuric dermatosis is the legs (pictures 13 14).
  • The condition is benign and mainly constitutes a cosmetic problem.
  • Several subtypes have been described, based on the appearance of the condition, for example, purpura pigmentosa progressiva (Schamberg disease) and lichen aureus (pictures 15 16).
  • Purpura generally refers to pin-prick or small patchy bleeding under the skin.
  • Purpura is also encountered in conditions affecting blood vessels (vasculitis) or blood platelets (thrombocytopenia), but it is rare in coagulopathies Easy Bruising, Petechiae and Ecchymoses.

Other leg rashes

  • Nodular diseases of the leg form a very mixed group as regards aetiology, and diagnosis often requires histologic confirmation.
  • These diseases include
  • Granuloma annulare is a skin condition usually encountered in school-aged children and in young adults. The majority of patients are female. The predominant sites in the lower extremities are the ankles (picture 19) and the metatarsal areas. Skin lesions on the legs may be more extensive.
  • Necrobiosis lipoidica (pictures 20 21 22) usually occurs on the front aspect of the legs as sharply defined ring-shaped plaques with an atrophic centre, which may ulcerate. The aetiology is unknown but may be associated with diabetes.
  • In Borrelia infection Lyme Borreliosis (LB), erythema migrans may occur on a leg (picture 23).

Consultation

  • Prolonged and treatment resistant leg dermatitis may warrant a consultation with a dermatologist, as does a suspicion of rarer nodular diseases.
  • Contact allergy may be established by patch testing.
  • A vascular surgeon should be consulted if venous insufficiency that lends itself to surgical correction is suspected.

References

  • Sundaresan S, Migden MR, Silapunt S. Stasis Dermatitis: Pathophysiology, Evaluation, and Management. Am J Clin Dermatol 2017;18(3):383-390. [PubMed]
  • Ely JW, Rosenfeld S, Seabury Stone M. Diagnosis and management of tinea infections. Am Fam Physician 2014;90(10):702-10. [PubMed]
  • van Zuuren EJ, Fedorowicz Z, El-Gohary M. Evidence-based topical treatments for tinea cruris and tinea corporis: a summary of a Cochrane systematic review. Br J Dermatol 2015;172(3):616-41. [PubMed]