| Entity | Defining phenotype / distribution | Onset / course | Inheritance / genetic evidence | Suggested HPO terms | Key diagnostics | Evidence-supported treatment | Evidence limitations |
|---|---|---|---|---|---|---|---|
| Umbrella keratosis pilaris atrophicans (KPA) | Follicular keratotic papules with perifollicular erythema progressing to fibrosis/atrophy, scarring, and permanent hair loss; umbrella grouping that includes UO/KPA faciei, atrophoderma vermiculatum, and KFSD (pqac-00000000, pqac-00000001) | Usually begins in infancy or childhood; several reports note progression until puberty then relative stabilization, with permanent residual alopecia/scarring possible (pqac-00000001, pqac-00000003) | Disease-group term rather than a single molecular entity; genetic architecture heterogeneous. Established monogenic cause exists for KFSD via MBTPS2, but isolated KPA umbrella diagnosis does not map to one confirmed causal gene in the retrieved evidence (pqac-00000003, pqac-00000007) | Follicular hyperkeratosis; Alopecia; Eyebrow alopecia; Cicatricial alopecia; Facial erythema; Cutaneous atrophy | Primarily clinical pattern recognition plus subtype-specific histopathology when scarring alopecia or overlap is present; biopsy may show dilated keratin-plugged follicles, perifollicular inflammation, and fibrosis (pqac-00000001, pqac-00000003) | Symptomatic and subtype-directed: keratolytics, topical retinoids, topical corticosteroids, oral retinoids in selected inflammatory disease, and laser procedures in case reports/small series (pqac-00000003, pqac-00000016, pqac-00000018) | No unified diagnostic criteria, no prevalence estimates, and no umbrella-level randomized trials identified; evidence dominated by case reports/series (pqac-00000001, pqac-00000018) |
| KPA faciei / ulerythema ophryogenes (UO) | Inflammatory keratotic papules and erythema beginning in the lateral eyebrows, spreading medially; may extend to cheeks and less often forehead/scalp; leads to eyebrow alopecia/scarring (pqac-00000000, pqac-00000006, pqac-00000017) | Begins at birth or soon after / early infancy; often progresses through childhood and may improve after puberty, but scarring can leave permanent hair loss (pqac-00000000, pqac-00000001, pqac-00000017) | Familial cases reported, often described as autosomal dominant with variable penetrance; strong syndromic association with RAS/MAPK disorders (Noonan, CFC, related syndromes), but retrieved evidence supports association rather than a single established cause for isolated UO. In CFC, UO occurred in 90% (55/61) of mutation-positive individuals; MAP3K1-associated Swyer syndrome case also reported (pqac-00000001, pqac-00000013, pqac-00000017) | HP:0000204 Eyebrow sparse; keratosis pilaris; facial erythema; scarring alopecia; madarosis | Clinical diagnosis; consider evaluation for syndromic features/RASopathy if dysmorphism, cardiac disease, developmental findings, or widespread ectodermal findings are present. Histology in overlap disease shows keratin plugging, infundibular atrophy, lymphocytic perifollicular infiltrates, fibrosis (pqac-00000001, pqac-00000013) | Topical retinoids, keratolytics (urea/lactic acid/salicylic acid), low-potency topical steroids used symptomatically; limited response reported in a MAP3K1 case. For erythematous disease, a cited 595-nm pulsed-dye laser series (n=10) achieved complete resolution in 3 and >75% improvement in 7, mainly reducing erythema (pqac-00000016, pqac-00000017) | Evidence mainly case reports and small uncontrolled laser series; effect on restoring eyebrow hair appears limited once scarring is established; causation for isolated UO remains uncertain in retrieved sources (pqac-00000016, pqac-00000017) |
| Atrophoderma vermiculatum / atrophoderma vermiculata | Symmetric follicular erythematous papules of cheeks, often preauricular, evolving into pitted reticulated “worm-eaten” / “honey-combed” atrophy and scarring (pqac-00000000, pqac-00000018) | Usually childhood onset; generally slow progressive worsening (pqac-00000018) | Considered within KPA spectrum, but isolated AV causal genetics remain uncertain in retrieved evidence. Older reports mention possible chromosomal associations (e.g., 18p deletion), but no firmly established recurrent monogenic cause was retrieved here (pqac-00000006, pqac-00000018) | Cutaneous atrophy; Facial scar; Follicular hyperkeratosis; Cheek lesion | Clinical morphology plus histopathology when needed: early keratotic follicular plugging/perifollicular inflammation; later follicular and sebaceous gland atrophy with dermal fibrosis (pqac-00000018) | Case-report support only for topical tretinoin and 35% trichloroacetic acid chemical peeling with partial response; literature cited in review/case reports also mentions CO2 laser, 585-nm pulsed-dye laser, dermabrasion, cryotherapy, and isotretinoin for inflammatory activity (pqac-00000018) | No curative therapy identified; very sparse evidence base, almost entirely single-patient reports; long-term benefit of cosmetic procedures hard to judge (pqac-00000018) |
| Keratosis follicularis spinulosa decalvans (KFSD) | Diffuse follicular hyperkeratosis with progressive cicatricial alopecia of scalp, eyebrows, and eyelashes; may include facial erythema, keratosis pilaris on trunk/extremities, photophobia, and ocular inflammation (pqac-00000002, pqac-00000004, pqac-00000005) | Infancy or childhood onset; scalp alopecia typically progresses through childhood/early adolescence; some reports note progression until puberty with permanent scarring alopecia (pqac-00000001, pqac-00000004, pqac-00000005) | Established MBTPS2-related disorder with X-linked inheritance; study of 15 affected males from 13 unrelated families identified 11 missense mutations and genotype-phenotype correlations. Variant c.1523A>G p.(Asn508Ser) caused mild KFSDX in three unrelated families (pqac-00000007, pqac-00000008, pqac-00000011) | HP:0002556 Scarring alopecia; HP:0002209 Keratosis pilaris; HP:0000656 Eyelash alopecia; HP:0000204 Eyebrow sparse; photophobia | Diagnosis is clinical plus pathology; trichoscopy can show perifollicular hyperkeratosis, absent follicular ostia, tufted folliculitis/elongated vessels, yellow dots with dystrophic hairs. Histopathology shows decreased sebaceous glands and follicular units with diffuse fibrosis (pqac-00000002, pqac-00000014, pqac-00000015) | Best evidence is low-level but more specific than other KPA forms: keratolytics plus isotretinoin 0.3 mg/kg/day for 6 months produced complete facial resolution and scalp improvement in one report; subsequent minoxidil 5% twice daily increased hair density. Acitretin improved follicular ichthyosis/eyelash regrowth in related MBTPS2 disease but not established alopecia (pqac-00000014, pqac-00000010) | Despite established gene causation, treatment evidence remains limited to case reports/reviews; no disease-specific controlled trials identified; irreversible scarring limits hair recovery even with treatment (pqac-00000014, pqac-00000015) |


*Table: This compact table summarizes the keratosis pilaris atrophicans spectrum and separates clinically defined entities from the genetically established MBTPS2-associated KFSD subtype. It is useful for disease knowledge-base curation because it aligns phenotype, course, genetics, diagnostics, treatment evidence, and uncertainty in one place.*