What types of alopecia explain diffuse scalp thinning, shedding of long hair shafts with small roots, and an oily, itchy scalp with dandruff and inflamed follicles in a 33‑year‑old woman?

Differential Diagnosis of Diffuse Hair Loss with Scalp Inflammation

Your presentation—diffuse thinning with long hairs shedding with roots, increased dandruff and oiliness, and an itchy, tender scalp with inflamed follicles—most strongly suggests telogen effluvium complicated by seborrheic dermatitis or possibly early androgenetic alopecia with concurrent scalp inflammation, rather than classic alopecia areata. 1, 2

Primary Diagnostic Considerations

Telogen Effluvium (Most Likely)

• Telogen effluvium is the most common cause of diffuse hair loss in adult women and presents with abrupt, generalized shedding of normal club hairs (long shafts with small bulb-like roots) 2–3 months after a triggering event such as illness, stress, surgery, or nutritional deficiency 2, 3
• The shedding of long hairs with attached roots is pathognomonic for telogen effluvium, distinguishing it from alopecia areata which shows exclamation-mark hairs 1, 2
• Up to 80% of telogen effluvium cases with duration <1 year resolve spontaneously once the trigger is removed 4
• Common triggers include iron deficiency, thyroid dysfunction, rapid weight loss, severe emotional stress, or recent illness 1, 2

Androgenetic Alopecia (Female Pattern Hair Loss)

• Female pattern hair loss presents with gradual diffuse thinning over the central scalp and widening of the central part, with preservation of the frontal hairline 2, 5, 6
• Typically begins between ages 12–40 years and is characterized by miniaturization of hair follicles due to androgen sensitivity 5
• The scalp itself should not show inflammation, dandruff, or tenderness—these features suggest a concurrent condition 1, 3
• Dermoscopy would show hair diameter diversity and miniaturized hairs rather than yellow dots or exclamation-mark hairs 1

Seborrheic Dermatitis (Concurrent Scalp Condition)

• Your symptoms of increased oiliness, dandruff, itching, and tender inflamed follicles strongly suggest seborrheic dermatitis complicating the underlying hair loss 7
• This inflammatory scalp condition can coexist with telogen effluvium or androgenetic alopecia and may worsen hair shedding 7
• The presence of scalp inflammation and scaling distinguishes this from uncomplicated pattern hair loss 1, 3

Diffuse Alopecia Areata (Less Likely)

• Diffuse alopecia areata would show yellow dots and exclamation-mark hairs on dermoscopy, not long hairs with roots 1, 4
• Alopecia areata typically presents without scalp inflammation, oiliness, or dandruff 1, 3
• The scalp should appear normal without tenderness or follicular inflammation 1

Essential Diagnostic Workup

Clinical Examination

• Perform dermoscopy to look for yellow dots and exclamation-mark hairs (alopecia areata) versus hair diameter diversity and miniaturization (androgenetic alopecia) 1, 4
• Examine the pattern: diffuse central thinning with frontal hairline preservation suggests androgenetic alopecia, while patchy loss suggests alopecia areata 4, 7
• Assess scalp for inflammation, scaling, and follicular involvement—these features point toward seborrheic dermatitis or tinea capitis rather than pure alopecia areata 1, 7
• Perform a gentle hair pull test at the margins to assess active shedding 1, 7

Mandatory Laboratory Testing

• Check serum ferritin (target ≥60 ng/mL for optimal hair growth), as iron deficiency is the most common nutritional cause of diffuse telogen hair loss 1, 2
• Measure TSH and free T4 to exclude thyroid disease, which commonly causes diffuse hair loss 1, 2
• Check vitamin D level (<20 ng/mL indicates deficiency), as 70% of alopecia areata patients are deficient, though this is less relevant given your presentation 1
• Consider zinc level if resistant disease or poor nutrition is suspected 1

Conditional Testing

• Fungal culture is mandatory if scalp inflammation and scaling persist, to rule out tinea capitis 1, 4
• Check total testosterone, free testosterone, and SHBG only if you have signs of androgen excess such as acne, hirsutism, or irregular periods 1, 4
• Scalp biopsy is reserved for cases where the diagnosis remains uncertain after clinical examination and dermoscopy 1, 4

Management Algorithm

If Telogen Effluvium is Confirmed

• Identify and remove the triggering factor (stress, nutritional deficiency, illness, medication) 4, 2
• Correct iron deficiency to achieve ferritin ≥60 ng/mL 1
• Treat thyroid dysfunction if present 1, 2
• Provide reassurance that telogen effluvium is self-limited and resolves in 3–6 months once the trigger is addressed 4, 2
• Explain that the condition represents excessive shedding, not actual hair loss, and does not lead to baldness 2

If Androgenetic Alopecia is Confirmed

• Initiate topical minoxidil 2% solution twice daily as first-line therapy 4, 5
• Consider combination therapy with oral finasteride 1 mg daily if monotherapy fails, though this requires careful discussion in women of childbearing age 4
• Treatment must be continuous; stopping will result in resumption of hair loss 4

Treat Concurrent Seborrheic Dermatitis

• Use antifungal shampoos (ketoconazole 2%) twice weekly to reduce inflammation, oiliness, and dandruff 7
• Consider topical corticosteroid solution for inflamed, tender areas, but avoid prolonged use 4

Critical Pitfalls to Avoid

• Do not confuse telogen effluvium (long hairs with roots) with alopecia areata (exclamation-mark hairs)—the shedding pattern is completely different 1, 2
• Do not order extensive autoimmune panels for straightforward cases; they add no value when the clinical picture is clear 1, 4
• Do not overlook scalp inflammation as a clue to seborrheic dermatitis or tinea capitis—pure alopecia areata or androgenetic alopecia should not cause an itchy, inflamed scalp 1, 7, 3
• Do not assume androgenetic alopecia requires hormonal testing unless signs of androgen excess are present 1, 4
• Address the psychological impact directly, as hair loss can cause significant distress even when medically benign 1, 4