What are the differential diagnoses that should be associated with plantar bulge? Let’s find out: Heel bulge Heel bulge backward is commonly associated with trisomy 13. Trisomy 13, also known as Patau syndrome, is due to chromosomal abnormalities. The deformities and clinical manifestations are much more severe than in trisomy 21. Craniofacial deformities include small head, defective forehead and forebrain development, small eyes, often with iris defects, wide and flat nose, 2/3 of children have cleft upper lip and often cleft palate, low ear position, auricular deformity, small jaws, other common polydactyly (toes), fingers overlapping each other, heel protrusion and midfoot convexity, forming the so-called rocker bottom foot. Males often have scrotal deformities and cryptorchidism, while females have clitoral hypertrophy, double vagina, bicornuate uterus, etc. Flatfoot Flatfoot (orthopedics), flatfoot syndrome is mainly due to some causes of foot pain caused by abnormal foot bone morphology, muscle atrophy, ligament contracture or chronic strain injury resulting in collapse of the longitudinal arch of the foot or loss of elasticity, also known as flatfoot. Flat feet can be congenital or acquired. In children, the arch is often formed at the age of 4 to 6 years, and most children and adolescents with flat feet are congenital. Adult flat feet can be a continuation of childhood flat feet or can be secondary to other causes, resulting in a collapsed arch. Symptomatic adults with secondary flat feet are referred to as adults with acquired flatfoot syndrome. There are many causes of secondary arch collapse such as joint degeneration, trauma, diabetes, rheumatoid arthritis, neuropathic lesions, tumors, and posterior tibial tendon insufficiency. Inability to plantar flex and inversion Posterior tibial nerve injury is manifested by inability to plantar flex and inversion of the foot. It is a developmental deformity that can be detected at birth due to spasm of the posterior tibial muscles in the ankle joint. Inversion of the foot can occur in one or both feet and is manifested during development due to abnormalities in the tendons and ligaments of the foot. The condition is a congenital foot deformity. Smooth round mass in the foot and ankle The symptoms of tenosynovial cyst present as a smooth round mass in the foot and ankle. Tendon sheath cysts are hemispherical, cystic, elastic masses containing jelly-like material that occur around the joint or tendon sheath. The etiology is unknown, but it is usually found on the dorsum of the wrist and dorsum of the foot, and may be related to chronic trauma.