A folliculosebaceous-apocrine hamartoma, also known as "follicular-apocrine hamartoma", is a benign proliferation of the folliculosebaceous-apocrine unit.

Follicular hyperplasia (or "reactive follicular hyperplasia" or "lymphoid nodular hyperplasia") is a type of lymphoid hyperplasia. It is caused by a stimulation of the B cell compartment. It is caused by an abnormal proliferation of secondary follicles and occurs principally in the cortex without broaching the lymph node capsule. The follicles are cytologically polymorphous, are often polarized, and vary in size and shape. Follicular hyperplasia is distinguished from follicular lymphoma in its polyclonality and lack of bcl-2 protein expression, whereas follicular lymphoma is monoclonal, and does express bcl-2).

Proliferating trichilemmal cysts (also known as a "Pilar tumor", "Proliferating follicular cystic neoplasm", "Proliferating pilar tumor", and "Proliferating trichilemmal tumor") are a cutaneous condition characterized by proliferations of squamous cells forming scroll-like structures.

A basaloid follicular hamartoma is a cutaneous condition characterized as distinctive benign adnexal tumor that has several described variants.

Some specific reactive lymphadenopathies with a predominantly follicular pattern:

- Rheumatoid arthritis

- Sjogren syndrome

- IgG4-related disease (IgG4-related lymphadenopathy)

- Kimura disease

- Toxoplasmosis

- Syphilis

- Castleman disease

- HIV-associated lymphadenopathy

- Progressive transformation of germinal centers (PTGC)

Lymphoid hyperplasia is the rapid growth proliferation of normal cells that resemble lymph tissue.

Isthmicoma (also known as "Infundibuloma," and "Tumor of the follicular infundibulum") are a cutaneous condition characterized by flat, keratotic papules of the head and neck, skin lesions that are usually solitary.

Inverted follicular keratosis is a skin condition characterized by asymptomatic, firm, white–tan to pink papules and considered as a subtype of seborrheic keratosis.

Alopecia mucinosa (also known as "Follicular mucinosis," "Mucinosis follicularis,", "Pinkus’ follicular mucinosis," and "Pinkus’ follicular mucinosis–benign primary form") is a skin disorder that generally presents, but not exclusively, as erythematous plaques or flat patches without hair primarily on the scalp and face. This can also present on the body as a follicular mucinosis and may represent a systemic disease.

PTGC is treated by excisional biopsy and follow-up. It may occasionally recur and in a small proportion of patients has been reported to subsequently develop Hodgkin lymphoma (usually nodular lymphocyte predominant Hodgkin lymphoma).

Trichoblastomas are a cutaneous condition characterized by benign neoplasms of follicular germinative cells. Trichoblastic fibroma is a designation used to characterize small nodular trichoblastomas with conspicuous fibrocytic stroma, sometimes constituting over 50% of the lesion.

Microscopically, inverted follicular keratosis is characterized as a well-circumscribed inverted acanthotic squamous proliferation containing squamous eddies and without significant atypia.

Colloid nodules, also known as adenomatous nodules or colloid nodular goiter are benign, noncancerous enlargement of thyroid tissue. Although they may grow large, and there may be more than one, they are not malignant and they will not spread beyond the thyroid gland. Colloid nodules are the most common kind of thyroid nodule.

Urticaria-like follicular mucinosis is a rare cutaneous disorder that occurs primarily in middle-aged men.

Progressive transformation of germinal centres (PTGCs) is a reactive lymph node process of undetermined cause.

Warty dyskeratoma must be differentiated from vulvar dysplasia, Bowenoid papulosis, squamous carcinoma, condyloma, and other viral-induced squamous lesions.

Improvement or stabilization of the condition has been reported with topical and intralesional corticosteroids, antibiotics, hydroxychloroquine, topical and oral immunomodulators, tacrolimus, and most recently, 5-alpha-reductase inhibitors. In one study, the use of anti-androgens (finasteride or dutasteride) was associated with improvement in 47% and stabilization in 53% of patients

Warty dyskeratoma, also known as an Isolated dyskeratosis follicularis, is a benign epidermal proliferation with distinctive histologic findings that may mimic invasive squamous cell carcinoma and commonly manifests as an umbilicated (Having a central mark or depression resembling a navel) lesion with a keratotic plug, WD have some histopathologic similarities to viral warts but it's not caused by HPV and the majority of these lesions display overall histopathologic features consistent with a follicular adnexal neoplasm. usually limited to the head, neck, scalp or face and vulva. Lesions are generally and sporadic and may be associated with a follicular unit. Oral involvement, particularly the hard palate, and genital involvement have been reported. it can also be thought of as one of the manifestations of focal acantholytic dyskeratosis, an epidermal reaction pattern that can be seen in several disorders, including Darier's disease and Grover's disease. But the main Difference between Darier disease and Warty dyskeratoma, is that Darier disease inherited dermatosis (autosomal dominant) consisting of multiple keratotic papules on the face, trunk, and extremities, while WD occurs as an isolated, noninherited, single keratotic nodule mainly confined to the head and neck as mentioned earlier.

Ectodermal dysplasia with corkscrew hairs is a skin condition with salient features including exaggerated pili torti, scalp keloids, follicular plugging, keratosis pilaris, xerosis, eczema, palmoplantar keratoderma, syndactyly, onchodysplasia, and conjunctival neovascularization.

Rombo syndrome is a very rare genetic disorder characterized mainly by atrophoderma vermiculatum of the face, multiple milia, telangiectases, acral erythema, peripheral vasodilation with cyanosis and a propensity to develop basal cell carcinomas.

The lesions become visible in late childhood, began at ages 7 to 10 years and are most pronounced on the face, At that time a pronounced, somewhat cyanotic redness of the lips and hands was evident as well as moderate follicular atrophy of the skin on the cheeks. In adulthood, whitish-yellow, milia-like papules and telangiectatic vessels developed. The papules were present particularly on the cheeks and forehead, gradually becoming very conspicuous and dominating the clinical picture. Trichoepitheliomas were found in 1 case. In adults, the eyelashes and eyebrows were either missing or irregularly distributed with defective and maldirected growth. Basal cell carcinomas were a frequent complication. The skin atrophy was referred to as vermiculate atrophoderma. Basal cell carcinomas may develop around the age of 35. Histological observations during the early stage include irregularly distributed and atrophic hair follicles, milia, dilated dermal vessels, lack of elastin or elastin in clumps. After light irradiation a tendency to increased repair activity was observed both in epidermis and in the dermal fibroblasts.

Histologic sections showed the dermis to be almost devoid of elastin in most areas with clumping of elastic material in other areas. The disorder had been transmitted through at least 4 generations with instances of male-to-male transmission.

Pruritic folliculitis of pregnancy is a dermatosis of pregnancy characterized by small follicular pustules scattered widely over the trunk, appearing during the second or third trimester, and resolving by 2 or 3 weeks after delivery.

Perforating folliculitis is a skin condition in humans characterized by discrete follicular keratotic eruptions involving mainly the hairy parts of the extremities.

Frontal Fibrosing Alopecia is the frontotemporal hairline recession and eyebrow loss in postmenopausal women that is associated with perifollicular erythema, especially along the hairline. It is considered to be a clinical variant of lichen planopilaris.

Atrophodermia vermiculata is also known as "Acne vermoulante", "Acne vermoulanti", "Atrophoderma reticulata symmetrica faciei", "Atrophoderma reticulatum", "Atrophoderma vermiculata", "Atrophoderma vermiculatum", "Atrophodermia reticulata symmetrica faciei", "Atrophodermia ulerythematosa", "Atrophodermie vermiculée des joues avec kératoses folliculaires", "Folliculitis ulerythema reticulata", "Folliculitis ulerythematous reticulata", "Folliculitis ulerythemosa", "Honeycomb atrophy", "Ulerythema acneforme" and "Ulerythema acneiforme"

Atrophodermia vermiculata presents with erythematous follicular papules on the cheeks in childhood and, with time, the lesions develop into pit-like depressions.