Growing Mass in an Adolescent
Am Fam Physician. 2021 Oct ;104(4):413-414.
A 17-year-old patient presented with a lump on the head. The patient first noticed the lump at 11 years old. It had been slowly growing over the previous few years. The lump was not painful and did not bleed. It occasionally itched and bothered the patient when they brushed their hair. The patient did not recall injury or trauma to the area. Physical examination revealed a skin-colored polypoid mass on the top of the patient's head, above the parietal area (Figure 1). The mass was raised and asymmetrical with slightly irregular borders. It measured 14 mm × 12 mm in size.
Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?
B. Compound nevus.
C. Dermal nevus.
D. Junctional nevus.
The answer is C: dermal nevus. Commonly called moles, nevi are benign tumors composed of nevus cells. They can be acquired or congenital. Nevi appear on 1% to 2% of newborns and increase in incidence throughout life, peaking in the 30s and 40s. Most nevi are benign. However, some, such as large congenital nevi and atypical moles, may become malignant. Congenital nevi are considered large in adults if they are at least 20 cm in diameter and in neonates if they are at least 9 cm on the head or neck or 6 cm on other areas.1–4
The three subtypes of nevi (compound, dermal, and junctional) are differentiated by the location of the nevus cells in the skin. Nevus cells typically start in the dermoepidermal junction and migrate into the dermis. During the transition, a lesion is considered a compound nevus. The development is sequential, and progression can stop at any point.3,5
The shape and size of dermal nevi vary widely. They can be warty, polypoid, or pedunculated. Like the other subtypes, dermal nevi can be hyperpigmented or pink or appear the same color as surrounding skin.1,5
Acrochordons are commonly known as skin tags. They are usually the color of surrounding skin but can be hyperpigmented. They are often pedunculated and range from 2 mm to 5 mm in size but can be larger. They increase in number with age and during pregnancy.6
Compound nevi are usually hyperpigmented or the color of surrounding skin with a smooth and elevated or warty surface. Elevation may increase with age. They are usually round or oval and symmetrical. Hair
Referencesshow all references
1. Habif TP. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 5th ed. Mosby; 2009....
2. Marcdante KJ, Kliegman R, Nelson WE, eds. Nelson Essentials of Pediatrics. 8th ed. Elsevier; 2019.
3. Perkins A, Duffy RL. Atypical moles. Am Fam Physician. 2015;91(11):762–767. Accessed August 27, 2021. https://www.aafp.org/afp/2015/0601/p762.html
4. Ryan E, Warren L. Birthmarks—identification and management. Aust Fam Physician. 2012;41(5):274–277.
5. Sardana K, Chakravarty P, Goel K. Optimal management of common acquired melanocytic nevi (moles): current perspectives. Clin Cosmet Investig Dermatol. 2014;7:89–103.
6. Higgins JC, Maher MH, Douglas MS. Diagnosing common benign skin tumors. Am Fam Physician. 2015;92(7):601–607. Accessed August 27, 2021. https://www.aafp.org/afp/2015/1001/p601.html
This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.
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