Table 2.

Aging Type Classification (ATC) System²⁷

Type	Appearance	Anatomic Changes
Type 1: Hypotrophic	Cheek appears flat or concave NLFs and marionette lines appear due to “pseudoptosis” (ie, loss of underlying soft tissue) of the skin, which becomes redundant Jawline skin sags	Hypotrophy of superficial (SMCF, SLF, MCF, SJF, and IJF) and deep fat compartments (medial and lateral SOOF and DMCF)
Type 2: Hypotrophic/ptotic	Cheek appears concave at the infraorbital area while appearing convex and ptotic at the nasolabial compartment Lower cheek slightly convex	Hypotrophy of deep fat compartments NLF and SMCF ptosis Ptosis of MCF, SJF, and IJF
Type 3: Ptotic/hypertrophic	Infraorbital area appears flat or slightly concave Convex nasolabial region Prominent nasolabial fold Convex lower cheek	Hypertrophy and ptosis of SMCF and NLF Hypertrophy and ptosis of MCF, SJF, and IJF Slight hypotrophy of deep fat compartments (L-SOOF, M-SOOF, DMCF)
Type 4: Hypertrophic/ptotic	Cheek appears concave only at the nasojugal groove but convex elsewhere and at the nasolabial region Convex lower cheek with demarcation of the LTCF	Hypertrophy with secondary ptosis of the superficial and deep fatty tissues of the cheeks Ptosis of the nasolabial fold accentuated by hypertrophy Hypotrophic LTCF

Note: Data from Fundaro et al.27

Abbreviations: Superficial fat compartments: IF, infraorbital fat; SMCF, superficial medial cheek fat; NLF, nasolabial fat; MCF, middle cheek fat; LTCF, lateral temporal-cheek fat; SJF, superior jowl fat; IJF, inferior jowl fat. Deep fat compartments: M-SOOF, medial suborbicularis oculi fat; L-SOOF, lateral suborbicularis oculi fat; DMCF, deep medial cheek fat; BF, buccal fat.