Table 1.

Follicular adnexal tumours. 86 cases in 54 articles ^a

Benign	Cases/Articles (81/51)	M/F (41/30)	Age range (4/93)	Max diameter range (1–30)	Clinical morphology aspect	Dermoscopy
Basaloid follicular hamartoma	3/31,33,121	3/0	14–64	3–7	2 HN and truncal papules in 2 Indian patients with multiple lesions	• 1: pinkish background, blue‐grey and brown globules, linear irregular vessels • 1: papillomatous and cobblestone pattern, brown‐black globules and dots and comedo‐like openings
					Solitary HN macule in a 64 y/o patients from Singapore	• 1: homogenous structureless blue pigmentation, no visible vessels
Inverted follicular keratosis	12/49,76,101,184	8/4	29–93	4–12	1 HN pigmented macule (black and brown) in a 93 y/o woman	• 1: eccentric black blotches and brown lines, no visible vessels
					11 solitary nonpigmented pink‐reddish papules (6) and nodules (5), mainly on the HN (6) and limbs (3 upper, 3 lower). Patients were all Caucasians.	• 6: pink‐white background + central crust (2) or ulceration (2) or whitish/orange structureless areas (2); vessels: mostly hairpin peripheral • 2: yellow central keratin mass, white structureless areas, scales and blood spots, polymorphous radial vessels (hairpin, comma, glomerular and linear irregular) surrounded by a white halo • 2: peripheral hairpin vessels surrounded by a white halo, central white‐yellow amorphous area with polymorphous vessels (glomeruloid with white halo, linear irregular, dotted) • 1: papillomatous surface, central dotted vessels surrounded by white halo
Tumour of the follicular infundibulum	2/1140	1/1	53–54	5–11	2 pinkish macules on lower limbs and trunk of 2 Caucasian patients	• 1: pinkish background and white lines; short peripheral linear vessels and dotted or more convoluted in the central part • 1: white central lines, homogenous brown pigmentation
Trichilemmoma (1 desmoplastic)	7/5 40,77,86,105,128	4/3	6/84	3/10	5 solitary, 2 multiple (Cowden syndrome). All nonpigmented HN papules, except one keratotic horny plaque in a 6 y/o Asian girl, on a sebaceous nevus.	All with 2 concentric areas: • Central: whitish structureless, umbilicated or hyperkeratotic • Peripheral: pinkish‐reddish, with red ‘iris‐like structures’ (3), b or short linear or crown vessels (4)
Trichoadenoma	2/2115,139	1/1	45/65	5/6	2 solitary HN pinkish papules	• 1: pink‐yellow background, multiple roundish white structures surrounded by thin linear and arborizing unfocused vessels • 1: multiple small roundish white structures, diffuse unfocused linear vessels; 1 blue‐grey globule peripheral
Trichofolliculoma	2/2141,66	2/0	48–62	8–10	2 HN brownish‐pinkish nodules	• 1: ‘firework pattern’: central brown area with radial dark brown projections assuming a crown shape (coarse granules), with no pigment network; no visible vessels • 1: bluish nodule with a white central area, shiny white structures, dotted vessels and a central scale
Trichoepitelioma desmoplastic	5/58,46,91,97,136	2/1	16–83	2–14	5 solitary whitish‐pinkish plaques	• All white background (ivory in 3) + white‐yellow clods/globules (4). Vessels: fine arborizing (3), linear crown (1), linear/serpentine (1)
Trichoepitelioma	9/98,49,64,99,100,127,161,174,181	3/5	8–60	3–10	All HN papules: 7 white‐pink; 2 brown‐blue. 4 patients had multiple lesions (1 Brooke‐Spiegler syndrome; 1 multiple familial trichoepithelioma)	• 7: whitish background + multiple white roundish structures • 2: pigmented structures: blue‐grey ovoid nests and peripheral dots (1); brownish background, irregular brown globules and blotches (1) • Vessels: arborizing thin with a few branches (7); short fine (2)
Trichoblastoma (1 adamantinoid)	16/969,94,97,145,146,149,150,159,202	5/6	22–77	1–20	1 patient with multiple nodules on HN and trunk 15 solitary nodules or plaques, mainly on HN, of which 9 pigmented (blue‐grey). 6 on sebaceous nevus	• 10: pigmented criteria: 5 blue‐grey homogenous areas (3 symmetrical); 3 blue ovoid nests; 2 homogenous brown areas • Other criteria: yellow clods, chrysalis and white‐yellow structureless areas • 6: pinkish background (described as pearly in 2 cases and with an orange hue in 1 case) • Other criteria: Milky‐red areas, thick white streaks and short fine radial linear vessels with a crown distribution in 1 case; central whitish veil surrounded by unfocused arborizing vessels not crossing the center of lesion in 1 case.
Fibrofolliculoma and Trichodiscoma (1 mixed)	5 (4 patients)/248,84	3/1	35–72	4	All pink‐red papules 1 on HN of a 72 y/o Caucasian woman, 3 on HN and 1 on trunk of 3 Asian patients with Birt‐Hogg Dubè syndrome	• All pinkish‐whitish background • 4 pigmented criteria: brown globules (2), brownish background (2) • Vessels: linear irregular and dotted (1); linear (1)
Panfolliculoma	1/1103	1/0	60	7	Pink‐reddish truncal nodule	• White central part with some crusts; peripheral unfocused thin arborizing low branching vessels not crossing the center
Pilomatricoma (2 anetodermic; 1 bullous)	16/123,12,28,68,86,93,97,111,115,182,194,200	7/8	4–75	4–30	All solitary nodules, mainly on HN (12) and upper limbs (3). 4 pigmented (blue). 1 on sebaceous nevus	• 5: red‐blue background + yellow structureless areas (2) and ulceration (2). Vessels: linear irregular (3), tortuous (1), polymorphous (1) • 3: pink background and white roundish structures + peripheral blue homogenous areas (2). Linear irregular (2) or polymorphous (1) vessels. • 4: milky‐ or purple‐red background, yellowish structureless areas, linear irregular vessels or arborizing vessels + white streaks (2) and blue‐grey globules (1) • 2: blue‐red areas and linear irregular vessels + white streaks and ulceration (1) or white‐yellow ovoid nests (1). • 1: ‘fishing net‐like’ pattern: white interlacing lines surrounding red globules • 1: clear lobular structure, homogenous yellow and pink areas, yellowish globules and white scales
Melanocytic matricoma	1/1138	1/0	65	10	Blue nodule on upper limbs of a Caucasian patient	• central white‐blue structureless area, peripheral pink background and structureless brown areas. Polymorphous vessels: dotted, linear irregular, hairpin and glomerular

Malignant	Cases/Articles (5/4)	M/F (4/0)	Age range (58/72)	Max diameter range (10–40)	Clinical morphology aspect	Dermoscopy
Pilomatrix carcinoma	1/1155	1/0	69	14	Solitary HN red‐purple nodule	• 1: white irregular areas, surrounded by homogeneous structureless purple/red areas. Fine arborizing and linear irregular vessels
Trichilemmal carcinoma	3/210,97	2/0	65–72	10–40	Solitary HN pink‐red nodules, 2 ulcerated	• 3: white‐pink background with polymorphous vessels (dotted glomerular, linear irregular and tortuous) + yellow crusts in 1 case
Trichoblastic carcinoma	1/1205	1/0	58	20	Ulcerated HN blue‐grey nodules	• 1: heterogeneous pigmentation with blue and black pigmented areas with a whitish veil

HN, head and neck.

^a See eReferences.

^b Iris‐like structure: radial morphology aspect with erythematous radial lines surrounded by white shiny areas, the redlines appeared thickened and highlighted at their outer end, presenting as red triangles or red projections.