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AlexanderSalava

Dermatological Diagnosis at a Glance

Essentials

  • Eczematous dermatitis, skin infections and benign skin tumours are the most common skin problems encountered by a general practitioner.
  • The diagnosis and treatment are usually based on the patient's history and clinical presentation.
  • If the diagnosis of a skin tumour remains unclear, taking a biopsy is worthwhile.

Examining the patient

  • History and a comprehensive clinical examination
  • Examine also the patient's palms, soles, nails, scalp, oral mucosa and the genital area. Examining these areas will often point towards the right diagnosis.
  • Family history is important e.g. in atopic dermatitis and psoriasis.
  • Ask the patient about factors at the workplace and free time that aggravate the condition.
  • Investigations
    • Full blood count may give diagnostic clues.
      • Eosinophilia: atopy, scabies, drug reaction, autoimmune diseases
      • Lymphocytopenia: viral exanthema, cutaneous lupus erythematosus
    • Fungal samples (for microscopy and culture) if necessary from a scaly rash
    • Bacterial samples from an eczematous area are only rarely of any benefit.
    • Patch testing may be indicated, under the supervision of a dermatologist, if contact allergy is suspected and in chronic eczema.
    • The diagnosis of a skin tumour with an unclear aetiology can be verified with a biopsy (e.g. a punch biopsy).

Diagnostic clues

A baby with dandruff

An adult with dandruff

  • In the northern countries every third person has seborrhoea Seborrhoeic Dermatitis in the Adult. In Central Europe the percentage is lower and even lower in the Mediterranean area. Diffuse dandruff on the scalp, mainly on the temples (pictures 123). Atopic dermatitis on the scalp of a young adult closely resembles seborrhoeic dermatitis, but the rash occurs also in other typical areas; an exact diagnosis is not necessary as the treatment is the same.
  • In psoriasis Psoriasis (picture 4), the lesions are well-demarcated and the scaling is thicker.
  • Lichen simplex nuchae (picture 5) may be a sign of atopy.
  • Tinea (ringworm) of the scalp Dermatomycoses is rare. At the site of the rash the hair becomes thin and brittle. Fungal cultures can be taken if suspected.
  • Tinea capitis is more common among patients with dark skin types, particularly in children (e.g. immigrants).

Dermatitis around the eyes

Angular cheilitis

  • Usually caused by contact dermatitis which is due to constantly wet and warm skin area. Patients often have atopic dermatitis too.
  • The same condition in an elderly person may be suggestive of ill-fitting dentures and an excessively deep bite (picture 7).
  • More rare predisposing factors include immunodeficiencies and diabetes, as well as deficiencies of iron, folate or vitamin B12. See also Cheilitis.

Cheilitis simplex (dry, cracked lips)

  • A sign of atopy
  • Affects paediatric patients who are at least partial mouth breathers.
  • Food allergy is also possible.

Other facial rashes

  • See also Facial Dermatoses.
  • Remember to differentiate acne and rosacea (papules dominate clinical picture) from eczematous diseases (patchy erythema and scaling).
  • Deliberate self-harm may be evident also on the face (picture 8).

Dermatitis of the palms

  • See Hand Dermatitis.
  • Symmetric dermatitis on the palmar surfaces in a young person is either irritant contact dermatitis or atopic dermatitis.
  • In an adult patient, the condition usually is irritant contact dermatitis or chronic dermatitis of unknown aetiology (picture 9), rarely allergic contact dermatitis.
  • Many occupational diseases may only manifest as hand dermatitis - enquire about the patient's employment.
  • Severe chronic irritant contact dermatitis of the palms (endogenous irritant contact dermatitis of the palms) may in some cases be a sign of excessive alcohol consumption. Smoking may also aggravate it (picture 10).
  • Unilateral palmar dermatitis is often tinea manuum (picture 11). A fungal culture is indicated.
  • Nummular dermatitis Nummular Dermatitis may also appear on the hands (picture 12).

Dermatitis of the fingertips

  • Fissured scaling on the fingertips (picture 13)
  • A sub-form of chronic dermatitis (endogenous irritant contact dermatitis of the palms). More common in older women. The condition is often chronic and persistent. Unknown aetiology.
  • Psoriasis may only appear on the fingertips.

Myxoid cyst

  • Myxoid cyst is a wart-like vesicle at the distal joint or in the nail wall of a finger or toe (pictures 14 15 16 17). It is often associated with osteoarthritis.
  • A recurrent cyst can be treated with liquid nitrogen cryotherapy, needle aspiration and cortisone injection or with surgery.

Patchy hyperkeratosis of the palms and soles

  • Usually a sub-form of chronic irritant contact dermatitis (endogenous irritant contact dermatitis of the palms). Aetiology is unknown. Usually encountered in patients in later adulthood and may occur in families.
  • Differential diagnosis may include psoriasis (picture 18) and sometimes also allergic contact dermatitis.

Groin rash

  • See Inguinal and Genital Skin Problems.
  • Seborrhoeic dermatitis (picture 19) and tinea cruris (jock itch; picture 20) are the most common at this anatomical site. Additionally, intertrigo (chafing of warm, moist apposing skin surfaces) associated with diabetes or obesity is common. Also psoriasis may cause symptoms in the groin (inverse psoriasis; picture 21), but it usually is found also in other skin areas.

Balanitis

  • See Balanitis, Balanoposthitis and Paraphimosis in the Adult.
  • Most cases are seborrhoeic dermatitis (picture 22). Check the scalp and other sites of predilection for seborrhoeic dermatitis.
  • May also be irritant dermatitis caused by excessive washing and soap.
  • Circinate balanitis (picture 23) is a manifestation of Reiter's syndrome and may be obscured by other inflammation.
  • Psoriasis and lichen planus (picture 24) appear as well-demarcated, chronic, slightly infiltrated patchy lesions.

Intergluteal cleft rash

  • Nearly always seborrhoeic dermatitis
  • May have led to the development of lichen simplex chronicus (neurodermatitis; picture 25).
  • May closely resemble lexural psoriasis (picture 26).

Itchy patch on leg

  • See Lower Leg Dermatitis.
  • Usually circumscribed neurodermatitis (pictures 27 28) or nummular eczema (pictures 29 30)
  • A thick reddish-blue patchy lesion may also be chronic hypertrophic lichen planus (picture 31).

Rash on the sole of the foot

  • Fissured scaling on the balls of the feet and under the toes in children is usually atopic dermatitis (pictures 3233).
  • Tinea pedis is rare in children under 15 years. In adults, the sites of predilection (pictures 34 35) for tinea pedis are under and between the toes.
    • Scaling across the lower portion of the foot in an adult may be moccasin tinea pedis (picture 36). A fungal culture is indicated.
    • Unilateral rash increases the likelihood of tinea pedis.
  • There are two main types of plantar warts Warts (Verruca Vulgaris) (picture 37) : common solitary warts that develop callosities and are therefore painful, and mosaic warts with a diameter of 2-3 mm that spread in a mat-like pattern. They usually occur in large numbers in a single group, more rarely in scattered groups.
  • A rash of the sole may also be triggered by sweating and maceration alone (picture 38).
  • Elderly persons often have physiological scaling and skin thickening (hyperkeratoses). Also chronic eczema and corns/calluses are common.

Urticaria

  • See Hives (Urticaria); picture 39.
  • The wheals should disappear from time to time or at least migrate within 24 hours.
  • If a wheal persists for longer than 24 hours, the diagnosis is usually not urticaria.
  • Triggering factors may include infections, drugs or allergies. Prolonged urticaria is usually spontaneous or physical urticaria of unknown cause.

Skin tumours and naevi (moles)

  • The great majority of skin tumours encountered by a general practitioner are benign.
  • It is not always possible to make a definitive diagnosis on the basis of clinical presentation alone.
  • Diagnosis can be confirmed with a biopsy, which can be taken from almost any skin lesion.
  • The need for a biopsy is usually based on a change noted on a tumour or mole, a risk assessment by the doctor and the patient's wishes.
  • See also Basal Cell Carcinoma Melanoma.

    References

    • Wilmer EN, Gustafson CJ, Ahn CS ym. Most common dermatologic conditions encountered by dermatologists and nondermatologists. Cutis 2014;94(6):285-92. [PubMed]
    • Fleischer AB Jr, Herbert CR, Feldman SR ym. Diagnosis of skin disease by nondermatologists. Am J Manag Care 2000;6(10):1149-56. [PubMed]
    • Ruiz de Luzuriaga AM, Mhlaba J, Roman C. Primary Care of Adult Women: Common Dermatologic Conditions. Obstet Gynecol Clin North Am 2016;43(2):181-200. [PubMed]
    • Baron SE, Cohen SN, Archer CB ym. Guidance on the diagnosis and clinical management of atopic eczema. Clin Exp Dermatol 2012;37 Suppl 1():7-12. [PubMed]
    • Hahnel E, Lichterfeld A, Blume-Peytavi U ym. The epidemiology of skin conditions in the aged: A systematic review. J Tissue Viability 2017;26(1):20-28. [PubMed]