What is a Caruncle?
The caruncle is a small, fleshy, nodular structure located at the inner corner of the eye (medial canthus), positioned medial to the plica semilunaris, and is composed of diverse tissue types including conjunctival epithelium, skin elements, hair follicles, sebaceous glands, sweat glands, and accessory lacrimal tissue. 1, 2
Anatomical Composition
The caruncle's unique histological makeup explains why it can develop a wide variety of lesions:
- Contains both mucosal and epidermal elements, making it susceptible to lesions typically found in skin, conjunctiva, or lacrimal glands 2, 3
- Includes hair follicles, sebaceous glands, sweat glands, and accessory lacrimal tissue in addition to conjunctival tissue 1, 2
Clinical Significance
Lesion Characteristics
- Caruncular lesions are uncommon, and clinical preoperative diagnosis is difficult, being accurate in only about 50% of cases 2
- The vast majority of caruncular lesions are benign, with nevi being the most common, followed by cystic lesions, oncocytoma, papilloma, and sebaceous gland hyperplasia 2, 4
- Malignant lesions are rare but potentially fatal, including melanoma, sebaceous carcinoma, basal cell carcinoma, squamous cell carcinoma, and lymphoproliferative disease 5, 6
Warning Signs of Malignancy
Look for these specific clinical features that suggest malignancy:
- Rapid growth, pigment deposition, ulcerated surface, and bleeding 6
- Increased pigmentation suggests melanoma 6
- Yellow-colored deposition suggests sebaceous carcinoma 6
- Salmon-pink hue suggests lymphoproliferative disease 6
- Age over 60 years increases risk, as 8 of 9 oncocytomas and both malignant lesions in one series occurred in patients older than 60 4
Management Approach
- Any suspected malignant lesion should be excised and examined histopathologically by an experienced pathologist, even though malignancy is often clinically overestimated 2
- Excision is indicated for atypical presentation, suspected carcinoma, mass effect causing discomfort or tearing, or cosmetic concerns 3
- Metastases can occur to cervical and preauricular lymph nodes, and systemic dissemination may involve lung, brain, liver, skin, bone, and gastrointestinal tract 1, 6