Make the Diagnosis

A 77-year-old white male with a history of multiple nonmelanoma skin cancers as well as melanoma presented with an asymptomatic pink plaque on the vertex of the scalp.

A 77-year-old white male with a history of multiple nonmelanoma skin cancers as well as melanoma presented with an asymptomatic pink plaque on the vertex of the scalp. The lesion appeared rather quickly, over the span of a few weeks.

What's the diagnosis?

Merkel cell carcinoma

Atypical fibroxanthoma

Squamous cell carcinoma

Amelanotic melanoma

Atypical fibroxanthoma (AFX) is a low grade, indolent sarcoma that tends to occur on sun-exposed areas, such as the head and neck. White individuals over aged 50 years are more frequently affected. Both genders are equally affected, and 25% of cases occur on the covered areas (trunk or extremities) of younger patients. Clinically, lesions present as pink to red plaques or nodules that exhibit rapid growth. Ulceration or crusting may be present. Causes of AFX include ultraviolet radiation and ionizing radiation. AFX is considered a superficial variant of malignant fibrous histiocytoma (MFH), the most common soft tissue sarcoma of adults. Clinically, MFH involves deeper tissues than does AFX, often on the thighs or buttocks. MFH is a more aggressive malignancy that regularly metastasizes.

Dr. Donna Bilu Martin

Another AFX case, in a 94-year-old white female, who presented with a 1-month history of an asymptomatic, pink nodule on her left eyebrow. She has a history of non-melanoma skin cancers on the face.

Histologically, the tumor occurs as a dermal proliferation of “bizarre” spindle cells, epithelioid cells, and atypical histiocytes. Vesicular changes may be present in the nucleus or cytoplasm of the spindle cells. Mitotic figures are present. Multinucleated giant cells may be present. Solar elastosis is often seen, as well. Vimentin and histiocyte stains are positive. Unlike melanoma, S-100 staining is minimal. Unlike squamous cell carcinoma, prekeratin staining is negative. CD34 is negative. AFX resembles MFH histologically.

Surgical excision by the Mohs procedure is preferred over wide excision as there is a risk of recurrence. AFX rarely metastasizes. This is more likely if inadequately excised or the patient is immunosuppressed. Sun protective practices, such as applying and reapplying sunscreen regularly, wearing sun protective clothing, and avoiding excessive UV exposure during peak hours is recommended.

Dr. Donna Bilu Martin, a dermatologist in private practice in Aventura, Fla.

Dr. Donna Bilu Martin

This case and photo were submitted by Dr. Bilu Martin.

Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at edermatologynews.com. To submit a case for possible publication, send an email to dermnews@mdedge.com.

Next Article: