• Tinea cruris usually spares the scrotum, whereas your pigmentation is around the scrotum. This makes a past fungal rash possible but not certain. - Textbook of Family Medicine, p. 940
• Pigmented groin patches can also occur with erythrasma, friction, lichen simplex, normal genital pigmentation, and, if the area is velvety or thickened, acanthosis nigricans related to insulin resistance.

What to do now

1. See a dermatologist before starting pigment creams.
   If there is any subtle active scaling, a simple KOH skin scraping can check for fungus. A Wood's-lamp exam may identify erythrasma, which fluoresces coral-pink. If the diagnosis remains unclear, the dermatologist may consider dermoscopy or, rarely, biopsy.
2. Do not use an antifungal unless there is active infection.
   With no current itch, scale, or advancing red edge, treating presumed fungus is unlikely to remove pigment that has remained for years.
3. Gentle groin care
   • Keep the area dry after bathing and exercise.
   • Use loose cotton underwear and avoid tight, abrasive clothing.
   • Avoid friction, scrubbing, perfumes, deodorant sprays, “intimate washes,” and harsh soaps.
   • Do not use over-the-counter steroid-antifungal combination creams. Steroids can thin genital skin and can mask or worsen an infection.
4. Pigment treatment should be cautious and dermatologist-supervised.
   PIH can fade slowly, but pigment present since adolescence may be deep and may not fully clear. Textbook guidance notes that topical hydroquinone 2% to 4% can help epidermal PIH over 3 to 6 months, but irritation itself can worsen pigmentation. - Dermatology 2-Volume Set 5e, p. 1340
   Because groin and scrotal skin is sensitive, a dermatologist may choose a low-irritation option such as azelaic acid, niacinamide, or carefully supervised hydroquinone rather than a strong retinoid or acid peel. Do not apply hydroquinone, tretinoin, glycolic acid, chemical peels, or laser treatment to the scrotum or adjacent folds on your own. Procedures and irritant products may cause more PIH or permanent lighter patches. DermNet's PIH guidance makes the same point about topical and procedure-related irritation.
5. Consider glucose screening if the dark area is velvety/thickened, there are similar patches on the neck or armpits, or there is overweight, family history of diabetes, or increased waist size. Acanthosis nigricans can involve the groin and is associated with insulin resistance.

Seek review sooner if

• It starts itching, scaling, spreading, cracking, or becoming red
• There is a sharply defined active border
• New lesions occur elsewhere
• It becomes raised, ulcerated, painful, or bleeds
• You have unexplained weight loss or rapid widespread darkening

Practical management

• No antifungal or topical steroid is needed now if there is no itch, redness, scale, or enlarging border.
• Reduce repeated irritation: loose cotton underwear, dry the folds gently after bathing/exercise, avoid friction, shaving-related irritation, fragranced products, “intimate” washes, and scrubbing.
• Do not use OTC mixed steroid-antifungal-lightening creams, strong acids, bleaching agents, peels, or lasers in this region. Genital and fold skin can become irritated, which can produce even darker PIH or patchy lightening.

Treatment for the pigment

1. Azelaic acid 10% to 15%, thin layer to affected external groin skin only, initially 2 to 3 nights per week. Stop if burning, redness, or itch develops. Do not apply to scrotal mucosal-type skin or broken skin.
2. If tolerated and if the dermatologist considers it appropriate, hydroquinone 2% to 4% can be used for a limited course, commonly around 8 to 12 weeks, then reassessed. Textbook guidance suggests epidermal PIH may lighten over 3 to 6 months, but irritation can aggravate pigmentation. - Dermatology 2-Volume Set 5e, p. 1340
3. Avoid routine tretinoin, glycolic acid, salicylic acid, and triple-combination hydroquinone/tretinoin/steroid cream in the groin unless a dermatologist specifically directs their use.

One diagnostic caveat