A 5-year-old boy presents with a small nodule on the sclera as shown in the image below. What is the likely diagnosis?

Explanation

## Correct Answer: B. Dermoid A scleral dermoid in a 5-year-old child is a congenital choristoma—ectopic tissue (typically epidermis, hair follicles, and sebaceous glands) that arises from incomplete separation of surface ectoderm during embryogenesis. The key discriminator is the **age of presentation (childhood) combined with a small, firm, yellowish nodule at the limbus or on the sclera**. Dermoids are typically located at the inferotemporal quadrant (most common site) and present as a well-defined, non-progressive mass. Unlike pterygium or pinguecula (which are degenerative lesions of adults), dermoids are present from birth or early childhood and do not show the vascular, inflammatory, or progressive characteristics of pterygium. Histologically, dermoids contain mature skin elements (hair, sebaceous glands, sweat glands) within the sclera or episclera. In Indian pediatric ophthalmology practice, dermoids are recognized as the most common congenital episcleral/scleral lesion in children. Management is typically observation unless cosmetically bothersome or causing astigmatism; surgical excision is reserved for symptomatic cases. The benign, stable nature and childhood presentation make dermoid the definitive diagnosis here. ## Why the other options are wrong **A. Dermolipoma** — Dermolipoma is a congenital choristoma composed of fat and fibrous tissue, typically located in the superotemporal quadrant (opposite to dermoid's inferotemporal location). It appears as a soft, yellowish, mobile mass that is often mistaken for a mass but is actually a normal variant. Dermolipomas lack the firm consistency and hair/sebaceous elements seen in dermoids. The clinical presentation and location differ significantly from this case. **C. Pterygium** — Pterygium is a degenerative, vascular, inflammatory lesion of the conjunctiva and episclera that occurs almost exclusively in adults (rare before age 20) due to chronic UV exposure. It presents as a progressive, fleshy, triangular mass with prominent vessels extending from the medial canthus across the cornea. A 5-year-old with a stable nodule does not fit the epidemiology, clinical appearance, or progressive nature of pterygium. This is a classic age-based trap. **D. Pinguecula** — Pinguecula is a benign, degenerative lesion of the conjunctiva (not sclera) that occurs in middle-aged and elderly patients with chronic UV exposure. It appears as a yellowish, non-vascular nodule at the nasal or temporal limbus but is composed of hyaline degeneration and elastosis, not ectopic skin elements. The age of presentation (5 years) and congenital nature of the lesion rule out pinguecula entirely. ## High-Yield Facts - **Dermoid location**: Inferotemporal quadrant is the most common site; presents in childhood as a congenital choristoma. - **Histology of dermoid**: Contains mature skin elements (epidermis, hair follicles, sebaceous glands, sweat glands) within episclera or sclera. - **Pterygium vs. dermoid**: Pterygium is degenerative and adult-onset with UV exposure; dermoid is congenital and present from birth/early childhood. - **Management**: Observation is standard; surgical excision only if cosmetically bothersome or causing astigmatism or visual symptoms. - **Differential by age**: Dermoid in children; pterygium/pinguecula in adults—age is the key discriminator in Indian pediatric ophthalmology. ## Mnemonics **CHOP for Scleral Lesions in Children** **C**ongenital (Dermoid, Dermolipoma) vs **H**ealth-related (Pterygium—UV) vs **O**ther; **P**resentation age—Pediatric = Dermoid; Adult = Pterygium/Pinguecula. **DIP Rule: Dermoid, Inferior, Pediatric** **D**ermoid = **I**nferotemporal + **P**ediatric presentation. Use this to instantly rule out pterygium (adult, medial, progressive) and pinguecula (adult, nasal/temporal, degenerative). ## NBE Trap NBE pairs "scleral nodule" with pterygium to trap students who confuse congenital choristomas with degenerative adult lesions. The age (5 years) is the critical discriminator that eliminates pterygium and pinguecula entirely. ## Clinical Pearl In Indian pediatric ophthalmology clinics, a child presenting with a stable, firm, yellowish nodule at the inferotemporal limbus is almost always a dermoid until proven otherwise. Most parents seek consultation for cosmetic concerns rather than functional symptoms, and reassurance with observation is the standard approach in Indian practice. _Reference: Parson's Diseases of the Eye (Indian edition), Ch. 8 (Conjunctiva and Sclera); Bailey & Love's Short Practice of Surgery (Ophthalmology section)_