Koebner Phenomenon: Café-au-Lait Spots Developing after a Secondary-Degree Burn in a Patient with Neurofibromatosis Type 1.

An 18-year-old woman with an established history of neurofibromatosis type 1 (NF-1) presented for her 1-year dermatologic follow-up. Physical examination revealed two subcutaneous nodules on her right arm, axillary freckling, scattered café-au-lait macules (CALMs) on the trunk, and a 12 cm × 17 cm hyperpigmented rectangular region on her right flank (Figure 1). The pigmented patch contained numerous new CALMs that were morphologically consistent with CALMs identified on prior examinations; neither the patch nor the CALMs within it were present at prior examinations. Interestingly, the appearance of the patch and associated CALMs was preceded by a rectangular-shaped, second-degree thermal burn. On further questioning, the patient revealed that she had burned herself with hot water 4 months prior to her presentation in clinic, and noted the development of multiple CALMs within the skin area of her prior burn approximately 4 weeks after the incident. Of note, her left flank had sparsely scattered CALMs, which was consistent with her prior skin examinations (Figure 2). A depigmenting cream was to be applied to the rectangular pigmented patch; unfortunately, post-inflammatory hyperpigmentation from the burn and the adjoining lesions resulting from the Koebner phenomenon continue to be refractory to treatment.

Dermatofibrosarcoma Protuberans: The Current State of Multidisciplinary Management.

Dermatofibrosarcoma protuberans (DFSP) is a rare, infiltrative, soft tissue tumor. It has a propensity for deep invasion but a low risk for distant metastasis. The classic presentation is a slowly progressive, painless, and erythematous to purpuric patch on the trunk or arms. A deep, subcutaneous punch biopsy or incisional biopsy should be performed for diagnosis in all suspected cases; wide undermining of the skin is to be avoided for minimizing the risk of tumor seeding and for retaining the feasibility of histopathologic examination of re-excisions. Histopathologic distinction of DFSP from dermatofibroma requires immunohistochemical assessment for CD34, factor XIIIa, nestin, apolipoprotein D, and cathepsin K. Management of this cutaneous sarcoma involves a multidisciplinary oncologic approach. Surgical excision is usually the first step in management. DFSP has a high propensity for local recurrence, even when surgical margins are negative; therefore, radiation therapy or rarely systemic therapy is recommended, especially for locally advanced or metastatic cases. The indolent nature of DFSP requires lifelong surveillance for recurrence; however, most recurrences occur within 3 years of the primary excision. The median time for the development of a local recurrence is estimated to be 32 months. An emerging theragnostic transmembrane receptor target, folate hydrolase-1 (FOLH1; prostate-specific membrane antigen), has been expressed in benign dermatofibromas and in high-grade sarcomatous phenotypes. These findings suggest that DFSP may also express FOLH1, which could allow for surveillance with FOLH1 PET/CT and antibody-mediated brachytherapy.