DIFFERENTIAL DIAGNOSIS: The Umbilicated Lesion

By: Glen D. Houston, DDS, MSD (gdhdds@heartlandpath.com)

HISTORY

A 68-year-old man presents to your office as a referral from his primary care provider. During your examination, an umbilicated lesion involving the right lower lip is observed. The patient states that the lesion has been present "for a few days and is painful to the touch." He also has a long history of alcohol use, smoking (tobacco and marijuana), and recently, vaping.

QUESTION #1

An appropriate differential diagnosis for this lesion might include: a. Keratoacanthoma b. Squamous cell carcinoma c. Basal cell carcinoma d. Ulcerated fibroma e. Erythema multiforme

ANSWER #1

An appropriate differential diagnosis should include: a. Keratoacanthoma b. Squamous cell carcinoma c. Basal cell carcinoma

All three of these entities may present as an umbilicated lesion with a raised, rolled border involving the lower lip.

A keratoacanthoma (a) is typically observed on actinically damaged skin, particularly the face, including the lower lip. This benign lesion has a clinical presentation and histologic characteristics similar to squamous cell carcinoma. This entity exhibits rapid growth and is typically observed in adult men.

Squamous cell carcinoma (b) of the lower lip typically presents as an oozing, crusty, symptomatic, ulcerated area. Eventually, this non-healing ulcer develops a raised, rolled border that is indurated. This lesion is much more common on the lower lip than the upper lip and is usually observed in adult men. Most squamous cell carcinomas arising on the lower lip are associated with a lengthy history of sun exposure.

Basal cell carcinoma (c) is also typically observed on sun-damaged skin, particularly the upper face, with more than 85% of the cases found in the head and neck region. Basal cell carcinoma is the most common form of skin cancer and is more common in men than in women. This neoplasm usually presents as a firm, painless papule that slowly enlarges and gradually develops a central depression with an umbilicated appearance.

Fibroma (d) is the most common "tumor" of the oral cavity. Although it can appear anywhere in and around the oral cavity, the buccal mucosa is the most common anatomic site. Fibroma would not be included in the differential diagnosis in this case because it typically presents as a smooth surfaced, dome-shaped nodule with a broad, sessile base that is asymptomatic and not ulcerated.

Although erythema multiforme (e) may present with a wide spectrum of clinical diseases, oral lesions typically begin as multiple erythematous patches that undergo epithelial necrosis and evolve into large, shallow erosions and ulcerations with irregular borders. Patients are usually men in the20- to 30-year-old age group. This condition is not considered in the present clinical differential diagnosis.

QUESTION #2 a. No surgical intervention and follow closely for 3–4months b. Consultation with a specialist c. Biopsy d. Exfoliative cytology

Which of the following procedures should be performed?

ANSWER #2

Following a biopsy, the following procedures are indicated in this case:

(b) Consultation with a specialist

(c) Biopsy

Consultation with a specialist (b) to determine optimal treatment and management of the patient is necessary. Additionally, biopsy (c) of the lesion in order to establish a definitive treatment format is essential.

The choices no surgical intervention, follow closely for 3–4 months (a) and exfoliative cytology (d) would be of no benefit in the management of this umbilicated lesion.

QUESTION #3

Following a biopsy and submission of the specimen for histologic examination, the following microscopic features are noted for this lesion: a flask-shaped, central zone of keratin; the surrounding surface epithelium forms a "lip" or "buttress" over the sides of the central zone, producing a raised, rolled border; at the deep, leading edge of the lesion, islands of squamous cells are noted; and cytologic atypia of the squamous cells is not prominent. The correct diagnosis is: a. Squamous cell carcinoma b. Keratoacanthoma c. Basal cell carcinoma d. Necrotizing sialometaplasia

ANSWER #3

The correct answer is keratoacanthoma (b). See Discussion section.

The other possibilities are not considered for the present case. Squamous cell carcinoma (a) arises from dysplastic surface epithelium and is characterized by invasive islands, ribbons, and cords of malignant squamous epithelial cells. Varying degrees of cellular and nuclear pleomorphism would be observed. Basal cell carcinoma (c) is composed of cells that are arranged into- well demarcated islands and strands that arise from the basal cell layer of the overlying surface epithelium and invade the underlying connective tissue. Epithelial islands typically demonstrate palisading of the peripheral layer of cells with a zone of "retraction" between the epithelial islands and the adjacent connective tissue. Necrotizing sialometaplasia (d) is a salivary gland lesion characterized by necrosis of salivary gland acini with an associated squamous metaplasia of the salivary gland ducts. The histologic features noted for squamous cell carcinoma, basal cell carcinoma, and necrotizing sialometaplasia are distinctive for these three entities. These histologic features are not observed in the present case.

Discussion

Only since 1950, after the publication of papers by Rook and Whimster and Musso and Gordon, has this fairly common lesion been accepted as a distinct clinical entity. The keratoacanthoma is a benign lesion that occurs on sun-exposed skin. The etiology is unknown, although genetic and viral factors have been considered.

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From a clinical standpoint, keratoacanthoma is most frequently observed in men between the ages of 50 and 70 years of age. Approximately 90% of the lesions have occurred on sun-exposed skin, with the cheeks, nose, and dorsum of the hands most often involved. The lesion occurs on the lips in roughly 10% of cases. Keratoacanthoma presents as an elevated, umbilicated or crateriform area with rapid enlargement and a depressed central plug or core. Because of this clinical presentation, the keratoacanthoma may resemble both squamous cell as well as basal cell carcinoma; however, the microscopic features are characteristic and, if untreated, the lesion will spontaneously regress within 6-24 months.

Microscopic features of the keratoacanthoma are characterized by an abrupt marginal change with marked hyperkeratosis. The lesion has a flaskshaped crateriform configuration (keratin plug) with superficial collarette (buttress) and a bulbous, expanded base composed of surface epithelium. Well-formed keratin islands are observed "dropping off" into the underlying connective tissue. Cytologic atypia of the squamous cells in these islands is not prominent.

Surgical excision is the treatment of choice. Waiting for spontaneous involution is not advisable for two reasons: (1) One cannot be assured clinically that the lesion is a keratoacanthoma rather than a malignant neoplasm, and (2) the scar created by surgery is often more cosmetically acceptable than that which develops from spontaneous regression. After excision, approximately 2% to 8% of treated patients experience recurrent, persistent disease.

About the Author:

Dr. Houston works at Heartland Pathology Consultants, PC in Edmond, OK. He can be contacted with questions at gdhdds@ heartlandpath.com

References

Eversole LR, Leider AS, Alexander G: Intraoral and labial keratoacanthoma. Oral Surg Oral Med Oral Pathol. 1982; 54:663-667.

Janette A, Pecaro B, Longergan M, et al: Solitary intraoral keratoacanthoma: report of a case. J Oral Maxillofac Surg. 1996; 54:1026-1030.

Mandrell JC, Santa Cruz DJ: Keratoacanthoma: hyperplasia, benign neoplasm or a type of squamous cell carcinoma? Semin Diagn Pathol. 2009; 26:150-163.

Musso L, Gordon H: Spontaneous resolution of a molluscum sebaceum. Proc R Soc Med. 1950; Nov;43(11):838-839.

Rook A, Whimster I: Kerato-acanthoma. Arch Belg Dermatol Syphiligr. 1950; Sep;6(3):137-146.

Rook A, Whimster I: Keratoacanthoma—a thirty year retrospect. Br J Dermatol. 1979; Jan;100(1):41-47.

Schwartz RA: Keratoacanthoma: a clinic pathologic enigma. Dermatol Surg. 2004; 30:326-333.

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