Cutaneous Metastases Masquerading as Solitary or Multiple Keratoacanthomas

To the Editor:

We read with interest the excellent Cutis articles on cutaneous metastases by Tarantino et al¹ and Agnetta et al.² Tarantino et al¹ reported a 59-year-old man who developed cutaneous metastases on the scalp from an esophageal adenocarcinoma. Agnetta et al² described a 76-year-old woman with metastatic melanoma mimicking eruptive keratoacanthomas.

Cutaneous metastases are not common. They may herald the unsuspected diagnosis of a solid tumor recurrence or progression of systemic disease in an oncology patient. Occasionally, they are the primary manifestation of a visceral tumor in a previously cancer-free patient. Less often, skin lesions are the manifestation of a new or recurrent hematologic malignancy.^3,4

The morphology of cutaneous metastases is variable. Most commonly they appear as papules and nodules. However, they can mimic bacterial (eg, erysipelas) and viral (eg, herpes zoster) infections or present as scalp alopecia.^5-7

Cutaneous metastases also can mimic benign (eg, epidermoid cysts) or malignant (eg, keratoacanthoma) neoplasms. Keratoacanthomalike cutaneous metastases are rare.⁸ They can present as single or multiple tumors.^9,10

In the case reported by Tarantino et al,¹ the patient had a history of metastatic adenocarcinoma of the esophagus. His unsuspected recurrence presented not only with a single keratoacanthomalike cutaneous metastasis on the scalp but also with another metastasis-related scalp lesion that appeared as a smooth pearly papule. We also observed a 53-year-old man whose metastatic esophageal adenocarcinoma presented with a keratoacanthomalike nodule on the right upper lip; additionally, the patient had other cutaneous metastases that appeared as an erythematous papule on the forehead and a cystic nodule on the scalp.⁸ Other investigators also observed a single keratoacanthomalike lesion on the left cheek of a 49-year-old man with metastatic esophageal adenocarcinoma.¹¹

Agnetta et al² described a patient with a history of malignant melanoma on the left upper back that had been excised 2 years prior. She presented with the eruptive onset of multiple keratoacanthomalike cutaneous metastases on the chest, back, and right arm.² The important observation of metastatic malignant melanoma presenting as multiple keratoacanthomalike cutaneous metastases pointed out by Agnetta et al2 confirms a similar occurrence reported by Reed et al¹² in a patient with metastatic malignant melanoma.

We also previously reported the case of a 68-year-old man with metastatic laryngeal squamous cell carcinoma (SCC) who developed more than 10 keratoacanthomalike nodules within a radiation port that extended from the face to the mid chest.¹⁰ In addition, other researchers have noted a similar phenomenon of keratoacanthomalike cutaneous metastases mimicking eruptive keratoacanthomas.¹³ Gil et al¹⁴ described a 40-year-old woman whose metastatic epithelioid trophoblastic tumor initially presented as 11 keratoacanthomalike scalp nodules; interestingly, the first nodule spontaneously regressed. Araghi et al¹⁵ reported a 58-year-old woman--with a stable SCC of the larynx that had been diagnosed 2 years prior and treated with chemoradiotherapy--in whom cancer progression presented as multiple keratoacanthomalike lesions in an area of prior radiotherapy.

In conclusion, cutaneous metastases presenting as new-onset solitary or multiple keratoacanthomalike nodules in either a cancer-free individual or a patient with a prior history of a visceral malignancy is uncommon. Although the clinical features mimic those of a single or eruptive keratoacanthomas, a biopsy will readily establish the diagnosis of cutaneous metastatic cancer. Metastatic esophageal carcinoma--either adenocarcinoma or SCC--can present, albeit rarely, with cutaneous lesions that can have various morphologies.⁸ Whether there is an increased predilection for patients with metastatic esophageal adenocarcinoma to present with single keratoacanthomalike cutaneous metastases with or without concurrent additional skin lesions of cutaneous metastases of other morphologies remains to be determined.