Reticulated pigmentary dermatosis (RPD): it is characterized by a triad of persistent, diffuse, reticulated hyperpigmentation, non-cicatricial diffuse alopecia, and nail dystrophy. It often presents with punctate palmoplantar keratoderma and hypoplastic dermatoglyphics.5

Naegeli–Franceschetti–Jadassohn syndrome (NFJS): persistent, reticulate, perioral, periocular, and cervical hyperpigmentation after 2 years. Nonetheless, the NFJS is gone in adolescence. It is associated with hypohydrosis, dental involvement, punctate keratoderma, and nail dystrophy.6

Congenital dyskeratosis: a triad of reticulate hyperpigmentation on neck, face, and trunk, along with leukoplakia and nail dystrophy.7 It is often associated with the development of malignancies such as Hodgkin's disease, oropharyngeal, esophageal, gastric, pancreatic, and squamous cell carcinomas.8

X-linked reticulate pigmentary disorder: in women, reticulate hyperpigmentation along Blaschko lines that often disappears in adulthood. In men, generalized reticulate hyperpigmentation that often appears between 4 and 5 years old with extracutaneous involvement.9

Reticular erythematous mucinosis: dermatosis associated with the gradual deposition of mucin in the dermis. It presents with erythematous, infiltrated, telangiectatic, and reticular papules in the midline of the chest, with or without itching. Reticular erythematous mucinosis predominantly affects young and middle-aged women. Heat, sweating, and sunlight exacerbate the symptoms.14

Erythema Ab Igne (EAI): chronic pigmentary disorder resulting from prolonged exposure to an infrared heat source. EAI shows areas of reticular erythema associated with hyperpigmentation, epidermal atrophy, and telangiectasias, often on the extremities. There may be an increased risk of malignant cutaneous transformation, including squamous cell carcinoma (SCC), which makes follow-up an important part of the management of this disease.15

Erythema infectiosum: reticular pattern of erythematous eruption on the trunk and limbs triggered by parvovirus B19.4 This pattern typically begins 1–4 days after the appearance of the classic “slapped cheek” rash. It disappears within 2–3 weeks but may reappear after exposure to UV rays and hot baths.2

Nekam's disease: chronic and progressive condition of unknown etiology, often considered a variant of lichen planus. It is characterized by an erythematous face with symmetrically distributed lichenoid keratotic papules of erythematous-violaceous to brown color. These papules cluster in linear or reticular patterns and predominantly affect the lower limbs.16

Physiological livedo reticularis (LR) or cutis marmorata: physiological response to cold exposure in newborns that disappears upon rewarming. It is characterized by a reticulate bluish vascular pattern involving the limbs and trunk symmetrically. It often resolves by the time the newborn is 6 months old.6

Pathological livedo reticularis: unlike its physiological counterpart, it does not resolve after warming the affected limb, may spread beyond the lower limb, and is often associated with severe systemic involvement of micro- and macro-circulation.17

Livedo racemosa: reticular pattern is often complete in LR, whereas livedo racemosa shows incomplete branching patterns.2 It exhibits a persistent, irreversible, and incomplete reticular network indicative of areas where blood flow is interrupted. When palpable, it is associated with vasculitis following the inflammation of blood vessel walls. If not palpable, it is suggestive of thrombotic disease.18

Retiform purpura: an advanced stage of livedo racemose, often associated with necrosis and ulceration indicative of severe systemic disease.18

Generalized essential telangiectasia: benign, asymptomatic, exclusively cutaneous condition characterized by localized or diffuse centripetal telangiectasias in a reticular configuration. The age of onset is often between the 3rd and 4th decades of life.19

Cutis marmorata telangiectasica congenita (CMTC): it is characterized by a reticular vascular mottling resembling physiological cutis marmorata. It stands out from the latter due to its persistent nature (even after rewarming), deep purple color, and association with skin atrophy or ulceration. Distribution can be localized, segmental, or generalized. More than half of the cases reported are associated with other abnormalities.2