Am Fam Physician. 2024;110(4):353-361
Author disclosure: No relevant financial relationships.
Patients commonly present to family physicians with skin findings, and distinguishing common benign skin tumors from potentially malignant tumors is important. Benign skin tumors can often be diagnosed by their history, distribution, and characteristic morphology. A biopsy or excision is indicated if there is diagnostic uncertainty or the lesion undergoes uncharacteristic or rapid change. A keratoacanthoma is a dome-shaped nodule with a central crater and can be difficult to distinguish from squamous cell carcinomas even with dermoscopy. Pilar cysts are typically benign, but rapidly growing types could have malignant qualities. Dermoid cysts, depending on their location, can have intracranial extension if untreated. Although dermatofibromas and seborrheic keratoses are benign, atypical presentations must be differentiated from melanomas. Sebaceous hyperplasia can mimic early basal cell carcinoma. Treatment options for cherry angiomas, acrochordons, slow-growing pilar cysts, and dermatofibromas should be individualized to skin type, lesion characteristics, and the patient's cosmetic preference. Generally, excision is the treatment of choice for keratoacanthomas, rapidly proliferating pilar cysts, and dermoid cysts. Cherry angiomas are treated with laser therapy and sebaceous hyperplasia with electrodesiccation. Common treatments for acrochordons and seborrheic keratoses are shave excision and cryotherapy. Pyogenic granulomas sometimes self-involute but bleed easily and often recur at the original site. They generally respond to shave excision and electrodesiccation. In patients with darker skin, treatment with cryotherapy and laser therapy should include discussions about hypopigmentation risk.
Family physicians often must identify and manage dermatologic diseases. A retrospective chart review over 2 years showed that about 36% of patients presenting to their primary care physician had at least one skin problem.1 Family physicians should be familiar with characteristics of common benign skin tumors and their diagnosis, including obtaining diagnostic skin biopsies. Table 1 summarizes some of the most common benign skin lesions.2–7
| Clinical recommendation | Evidence rating | Comments |
|---|---|---|
| Due to the difficulty in distinguishing keratoacanthomas from cutaneous squamous cell carcinoma, lesions suspicious for keratoacanthoma should be excised with a 5-mm margin.17,18 | C | Observational study and expert consensus |
| Although treatment of pyogenic granuloma is predominantly surgical, topical beta blockers are effective in children.20,21 | B | Multiple small clinical studies |
| Seborrheic keratoses are common benign lesions that may be treated cosmetically. However, a sudden increase in seborrheic keratosis lesions can indicate an underlying malignancy.2,13 | C | Expert consensus |
| Suspected dermoid cysts in infants and children should be referred for excision because they have the potential for intracranial extension.5,36 | C | Expert consensus |
| Condition | Characteristics | Differential diagnosis | Treatment | Clinical considerations |
|---|---|---|---|---|
| Acrochordon (skin tag) | Pedunculated; short, broad to narrow stalk; same color as surrounding skin or darker shades of brown and black | Senescent intradermal nevus | Scissor or shave excision Cryosurgery Electrodesiccation if they are bothersome to the patient or for cosmetic reasons | Associated with obesity and diabetes mellitus |
| Cherry angioma | Dome-shaped, small, bright red to deep purple, compressible papule | Pyogenic granuloma Amelanotic melanoma | Laser ablation Nonlaser therapy (cryotherapy, electrodesiccation, sclerotherapy) | Increased number associated with Fabry disease |
| Dermatofibroma | Solitary, firm, often hyperpigmented nodule | Dermatofibrosarcoma protuberans Kaposi sarcoma Basal cell carcinoma | No treatment required unless symptomatic or for cosmetic reasons | Associated with the dimple sign (Fitzpatrick sign) Multiple lesions may be associated with an underlying systemic immune disorder (e.g., systemic lupus erythematosus, HIV) |
| Dermoid cyst | Periorbital, soft, subcutaneous cyst that begins in childhood | Lipoma Epidermoid cyst | Surgical excision | Craniofacial origin; most are uncomplicated, but they may become complex and extend, requiring surgical coordination |
| Epidermoid cyst (epidermal inclusion cyst) | Firm, mobile, discrete superficial nodule with central punctum | Pilar cyst Lipoma | Intralesional steroid injection for inflamed lesion followed by surgical excision | Recurrent lesions can become more difficult to remove |
| Keloid | Elevated fibrous scar at site of previous dermal injury | Hypertrophic scaring | Intralesional injection Cryotherapy Surgical removal Immunotherapy | There is a 15-fold increase in risk of keloids in people with dark skin tones |
| Keratoacanthoma | Dome-shaped nodule with a central crater | Squamous cell and basal cell carcinoma | Surgical excision | Difficult to differentiate from squamous cell carcinoma on examination and dermoscopy; excision should be performed to diagnose and treat accordingly |
| Lipoma | Soft, mobile subcutaneous mass | Liposarcoma Epidermoid or pilar cyst | Incision with manual expression | Recurrence is common after removal |
| Pilar cyst | Single or multiple soft, subcutaneous nodules | Lipoma Epidermoid cyst | Generally treated for cosmesis Surgical excision if rapidly growing or proliferating | Likely benign, especially when soft; rare malignant potential |
| Plantar wart | Single or multiple, sandpaper-like lesions on plantar surface of the foot, may have black pinpoints | Heloma (corn) | Salicylic acid Cryosurgery Electrodesiccation Immunotherapy | Can spread through direct contact |
| Pyogenic granuloma | Red, yellow, or purple, friable papule or nodule; often surrounded by a scaly red or brown collarette; grows rapidly before stabilizing; bleeds easily | Spitz nevus Basal cell carcinoma Squamous cell carcinoma Amelanotic melanoma | Laser ablation Shave excision with electrodesiccation at the base Topical beta blockers are effective in children but used only with definitive treatment in adults | Rule out melanoma Refer patients with facial lesions |
| Sebaceous hyperplasia | Dome-shaped, yellow papules around hair follicles with central umbilication; yellow lobules on dermoscopy | Basal cell carcinoma | No treatment required If treatment desired for cosmetic reasons, options include cryosurgery, shave excision, laser ablation, electrodesiccation with curettage, chemical cautery, and oral isotretinoin | Lesions concerning for basal cell carcinoma should be removed and submitted for histopathologic evaluation |
| Seborrheic keratoses | Well-circumscribed, raised macules, papules, or plaques with a “stuck-on” appearance; same color as surrounding skin or darker | Atypical nevus Melanoma | No treatment required If treatment desired, options include shave excision, cryosurgery, laser ablation, topical hydrogen peroxide | Malignancy workup should be considered if multiple lesions develop rapidly |
ACROCHORDONS
Acrochordons (skin tags) are an outgrowth of normal skin and often appear as a pedunculated lesion. They occur in nearly one-half of the general population, with increased risk between 20 and 50 years of age.8 There is also increased prevalence among people with obesity or diabetes mellitus, likely due to hormonal imbalances. Areas of friction (e.g., axilla, neck, inguinal region) are commonly affected. Skin tags begin as small, oval excrescences that are the same color as surrounding skin and attached by a short, broad to narrow stalk.9 They can become irritated with trauma, such as catching on jewelry or clothing (Figure 1).
The stalks are easily removed with scissor excision, cryosurgery using liquid nitrogen, or electrodesiccation if they are bothersome to the patient or for cosmetic reasons. In patients with darker skin, narrow focus of the freeze area reduces the risk of hypopigmentation.10 Lesions are unlikely to recur after removal, but new lesions can develop in predisposed areas.
SEBACEOUS HYPERPLASIA
Sebaceous hyperplasia results from enlarged sebaceous glands. These lesions often appear as dome-shaped, asymptomatic, yellow papules with central umbilication, primarily on the forehead and cheeks. Hair follicles surrounded by yellow lobules on dermoscopy are diagnostic, and there can be single or multiple 1- to 4-mm lesions (Figure 2). No treatment is required. However, if desired for cosmetic reasons, therapeutic options include cryosurgery, shave excision, laser ablation, electrodesiccation with curettage, and chemical cautery. Oral isotretinoin can be used for widespread lesions.11,12
Sebaceous hyperplasia is benign but should be differentiated from basal cell carcinoma, which can be similar in appearance and location. Basal cell carcinoma generally appears more pink than yellow and enlarges over time. Dermatoscopic visualization of sebaceous hyperplasia reveals crown vessels at the base of the follicle and between lobules, whereas arborizing vessels and shiny white structures are seen with basal cell carcinoma.13 If lesions change in color or size, shave removal can be performed to rule out basal cell carcinoma.14,15
KERATOACANTHOMAS
Keratoacanthoma is an epithelial tumor that presents as a nodule with a central crater. The annual incidence is 104 out of 100,000 people, with peak occurrence between 65 and 71 years of age.16 It typically begins as a smooth, dome-shaped, red papule (resembling molluscum contagiosum) that expands over weeks to a 1- to 2-cm lesion with a central keratin-filled crater (Figure 3). Sun-exposed skin, such as arms and hands, is the most common location, followed by the trunk. Dermoscopy findings of keratoacanthomas share some features with squamous cell carcinoma and cannot be used to differentiate the two conditions.17
If untreated, keratoacanthomas usually stop growing in 6 weeks and regress slowly over 2 to 12 months, although some may progress. First-line therapy is typically surgical excision and histopathologic evaluation to confirm the diagnosis and completeness of tumor removal.17,18 Due to the difficulty in distinguishing keratoacanthomas from cutaneous squamous cell carcinoma, lesions suspicious for keratoacanthoma should be excised with a 5-mm margin.17,18 Mohs surgery, which is tissue sparing, can be considered for tumors that are deep or arise on the central face, ear, nose, and periocular or perioral skin. Other treatment options after obtaining a skin biopsy specimen include electrodesiccation and curettage, intralesional therapy with fluorouracil or methotrexate, radiation, and topical therapy. Early treatment may improve cosmetic outcomes by limiting damage to the skin and underlying structures.17
PYOGENIC GRANULOMAS
Pyogenic granulomas are rapidly growing papules that develop over weeks to months before stabilizing at less than 2 cm in size. Lesions are more common on the head and neck in children and on the trunk and extremities in adults. They are also common during pregnancy. Pyogenic granulomas are friable papules or nodules that can be yellow, red, or purple (Figure 4). These vascular tumors are often surrounded by a scaly red, brown, or white collarette (Figure 5). They often bleed or ulcerate, are difficult to control, and recur at the original site (unlike cherry angiomas). They sometimes regress spontaneously, but most patients receive treatment. The differential diagnosis includes cherry angiomas, Spitz nevi, amelanotic melanoma, and squamous or basal cell carcinoma.
A wide variety of treatment modalities have been studied, most commonly surgical excision, which offers the lowest overall recurrence rates and is most effective for larger lesions. Other effective treatment modalities include cryotherapy, electrodesiccation, and laser therapy.19,20 Studies in children show that topical beta blockers (e.g., timolol, propranolol) with occlusion are effective in treating pyogenic granuloma after several weeks. However, only a few small studies have evaluated the effectiveness of beta blockers in adults, and use was limited to adjunctive therapy with definitive treatment options.20,21 Recurrence rates for pyogenic granulomas range from 0% to 15% (average 4.5%) in small treatment studies.19
DERMATOFIBROMAS
Dermatofibromas (benign fibrous histiocytoma) originate from a dermal proliferation of fibroblasts. These lesions can occur after minor trauma, insect bites, viral infections, ruptured cysts, or folliculitis. They typically present as a solitary, firm, often hyperpigmented, 3- to 10-mm nodule (Figure 6). Lesions are often asymptomatic but can be pruritic when irritated. Diagnosis is usually based on clinical appearance and history. The lesions display dimple sign (Fitzpatrick sign), in which lateral pressure on the lesion produces a dimpling or retraction beneath the skin2,22 (Figure 7).
Although a solitary dermatofibroma may be an incidental finding, multiple dermatofibromas may be associated with an underlying systemic immune disorder, such as systemic lupus erythematosus or HIV.23 No treatment is required unless the lesion is symptomatic or the patient requests excision for cosmetic reasons. Excisional biopsy is preferred over shave biopsy to ensure clear histology and complete removal of the lesion, especially with atypical variants or suspicion for malignancy (e.g., lesion is painful, changes in shape or character, or is persistently pruritic).
SEBORRHEIC KERATOSES
Seborrheic keratoses, common after 30 years of age, are comprised of epidermal keratinocytes. They present as well-circumscribed, raised lesions with a “stuck on” appearance and color ranging from that of the surrounding skin or darker. Seborrheic keratoses can present as macules, papules, or plaques (Figure 8). The back is the most common location, but they can also occur on the abdomen, extremities, and face. Although usually asymptomatic, pruritus around the lesion is the most common symptom. Seborrheic keratoses do not require removal but are easily treated cosmetically with shave biopsy, cryosurgery, laser ablation, and topical hydrogen peroxide.24,25 Treatment of seborrheic keratoses with cryotherapy should involve counseling, as it can lead to hypopigmentation.10
Although rare, extensive seborrheic keratoses should alert the clinician to the possibility of an underlying systemic malignancy because seborrheic keratoses tend to proliferate with malignancy and regress with treatment.2,26,27 Due to their dark coloration, differentiating seborrheic keratoses from melanoma is important. Melanomas tend to vary more in color, with browns, blues, black, and grays.28 Dermatoscopic evaluation can help to differentiate these lesions. Dermatosis papulosa nigra lesions are histologically similar to seborrheic keratoses but have photodistribution on the face, head, and neck and occur in patients with darker skin tones (Figure 9).
CHERRY ANGIOMAS
Cherry angiomas, also known as De Morgan spots, are vascular papules that appear with increasing age. They are related to, but distinct from, infantile hemangiomas. They are dome-shaped, small (1 to 5 mm), bright red to deep purple, soft, compressible papules that bleed profusely with traumatic rupture and may blanch with pressure (Figure 10). They occur primarily on the trunk but also appear on the extremities. A recent review showed that laser therapy and nonlaser therapy (cryotherapy, electrodesiccation, sclerotherapy) are equally effective for cosmesis.29
Although cherry angiomas do not have malignant potential, in small studies, high numbers of cherry angiomas were associated with lighter skin color and a history of melanoma.30 The differential diagnosis includes pyogenic granuloma and amelanotic melanoma, which grows or changes over time and is often asymmetrical.
PILAR CYSTS
Pilar cysts (trichilemmal cysts) are slow-growing, intradermal cysts derived from outer hair follicle root sheath tissue and are found primarily on the scalp (Figure 11). These cysts have an appearance similar to epidermoid cysts and are sporadic or hereditary in patients with multiple pilar cysts.31 On ultrasonography, pilar cysts have increased echogenicity and more cystic features than epidermoid cysts.4 Although most pilar cysts are benign and slow-growing, rare forms, referred to as proliferating trichilemmal tumors, proliferate, grow rapidly, and have overlying skin changes and inflammation. This transitional type warrants excision because of the potential for malignant transformation (malignant trichilemmal cyst), accounting for less than 0.1% of all skin cancers.32 Rapidly growing pilar cysts are definitively diagnosed and treated with complete surgical excision and monitoring for recurrence.
EPIDERMOID CYSTS
Epidermoid cysts (epidermal inclusion cysts) are the most common type of cutaneous cyst. They are often called sebaceous cysts, but they do not contain sebaceous cells or material. The epidermoid cyst wall is stratified squamous epithelium that proliferates and results in an accumulation of keratin material within the dermis.33 Diagnosis is based on appearance and palpation of a firm, mobile, discrete superficial cyst or nodule. Careful inspection often reveals a central punctum. Epidermoid cysts usually present on the face, neck, or trunk. They can remain stable for prolonged periods or become inflamed, become infected, or spontaneously rupture.
Treatment is unnecessary unless desired by the patient and can be accomplished via simple excision with removal of the cyst and cyst wall. Inflamed or ruptured cysts often resolve spontaneously without therapy, although they may recur. Intralesional steroid injections can hasten resolution of inflamed cysts, followed by interval excision.34
The presence of multiple epidermoid cysts (Figure 12), or cysts in atypical locations (e.g., extremities), is associated with the autosomal dominant Gardner syndrome, colon polyps, and colon cancer. Epidermoid cysts are benign; however, malignancies develop rarely within or adjacent to the cyst (e.g., basal cell carcinoma, Bowen disease, squamous cell carcinoma, mycosis fungoides, melanoma in situ).2,35
DERMOID CYSTS
Although dermoid cysts are uncommon overall, they occur more often in infants and children. If untreated, small dermoid cysts grow and persist into adulthood with the potential for intracranial extension.36 Dermoid cysts are subcutaneous and have embryological origins associated with craniofacial development. They contain a mixture of squamous epithelium, keratin, sebaceous glands, and hair.6 Dermoid cysts occur primarily in the periorbital region, but can occur elsewhere on the head and neck, and are classified by their location5 (Figure 13). Imaging of the orbits can help differentiate superficial, freely mobile cysts from deeper cysts fixed to the underlying bone and may require coordination with a surgical specialist.5,36 Due to risk of deeper involvement, patients with a suspected dermoid cyst should be referred to an ear, nose, and throat specialist; dermatologist; or oculoplastic surgeon, depending on the location of the cyst.5,36
This article updates previous articles on this topic by Higgins, et al.,2 and Luba, et al.28
Data Sources: PubMed searches were completed in Clinical Queries using the key terms acrochordon, sebaceous hyperplasia, keratoacanthoma, pyogenic granuloma, dermatofibroma, seborrheic keratosis, cherry angiomas, dermoid cysts, epidermoid cyst, and pilar cysts. Other key words searched in PubMed: benign skin lesions, benign skin tumors, skin diseases, diagnosis, and treatment. The search included reviews, meta-analyses, randomized controlled trials, and clinical trials. We also searched Essential Evidence Plus, the Cochrane database, and UpToDate. We used references from 2006 and 2003 AFP articles on benign skin tumors. We critically reviewed studies that used patient categories such as race and/or gender but did not define how these categories were assigned, stating their limitations in the text. Search dates: June 14, 2023, and August 28, 2024.
