Terra firma-forme dermatosis.

KEY CLINICAL MESSAGE: Terra firma-forme is a benign condition characterized by cutaneous hyperpigmentation resembling dirt. Despite its typical clinical presentation, the disorder is not well-known by physicians. Prompt recognition can avoid useless investigations and therapies. Vigorous swabbing of the skin with isopropyl alcohol-soaked gauze pads results in complete healing.

A 70-year-old woman with metastatic breast cancer, treated with examestane for 2 months, presented for gradually increasing, asymptomatic clear-cut dark-brown velvety patches with light scaling on the trunk (Fig.1), resistant to water and detergents. Dermal scraping for direct microscopic and culture examination revealed resident flora.

Figure 1

Diffuse brown hyperpigmentation on the trunk.

Which is your diagnosis?

Answer

Terra firma-forme dermatosis, a probably underdiagnosed, benign disorder of keratinization of unknown etiology, affecting particularly children and young adults. It is characterized by cutaneous hyperpigmentation resembling dirt, not removable with usual hygiene measures [1]. Differential diagnoses include ichthyosis, pityriasis versicolor, postinflammatory hyperpigmentation, acanthosis nigricans, and iatrogenic eruptions. One-week treatment with local application of isopropyl alcohol usually determines complete resolution. Its prompt recognition may prevent unnecessary diagnostic procedures and improper treatments.