Joshua W. Trufant

Familial multiple pilomatrixomas as a presentation of attenuated adenomatosis polyposis coli

Pilomatrixomas are benign follicular tumors that occur most commonly in children. Rare multiple or familial pilomatrixomas have been associated with myotonic dystrophy and other disorders. Although sporadic pilomatrixomas and hybrid cutaneous cysts with pilomatrixoma‐like features have been observed in some kindreds with Gardner syndrome, an autosomal dominant form of familial adenomatous polyposis, no definitive association has been made with multiple or familial pilomatrixomas. Here we describe two siblings with multiple pilomatrixomas who were also found to have a family history of colonic adenocarcinoma. Genetic testing revealed a mutation in the 5′ portion of the adenomatous polyposis coli (APC) gene, in a region associated with an attenuated APC phenotype. These findings show that multiple pilomatrixomas may be the presenting symptom of patients with APC gene mutations.

Melanotic Schwannoma Arising in Association With Nevus of Ota: 2 Cases Suggesting a Shared Mechanism

Melanotic schwannoma is a rare markedly pigmented peripheral nerve sheath tumor comprising cells with prominent melanization and schwannian features. The psammomatous variety is associated with Carney complex, a multiple neoplasia syndrome with spotty skin pigmentation. We present the first 2 reported cases of melanotic schwannoma arising in patients with a history of nevus of Ota, a rare dermal melanosis believed to represent a failure of melanocyte migration to the epidermis during embryogenesis. Case 1 involves a 40-year-old woman with a 1.8-cm, deeply pigmented, trigeminal nerve mass and pigmentation of the maxillary sinus mucosa and bone. Case 2 involves a 53-year-old woman with a 1.5-cm mass adjacent to the clavicle. Microscopically, both masses consist of partially encapsulated epithelioid and spindle cells with abundant melanin pigment, arising in association with peripheral nerves. Morphological, immunohistochemical, and ultrastructural features support a diagnosis of melanotic schwannoma. No psammoma bodies are noted, and neither patient exhibits any additional features of Carney complex. Melanotic schwannoma is most often benign but has been associated with malignant behavior in some cases. Distinguishing this nerve sheath tumor from malignant melanoma can be difficult but is of great clinical importance due to differences in prognosis and treatment.

A transient epidermolysis bullosa simplex-like phenotype associated with bexarotene treatment in a G138E KRT5 heterozygote

Basal keratinocyte lysis is the hallmark histopathological finding of epidermolysis bullosa simplex (EBS), a group of rare heritable mechanobullous disorders characterized by intraepidermal blister formation and skin fragility. Over 100 mutations, found predominantly in the genes encoding keratins 5 and 14 (KRT5, KRT14), have been described to account for a variety of clinical subtypes. EBS with mottled pigmentation (EBS‐MP) is a rare variant featuring childhood‐onset reticulate hyperpigmentation and focal palmoplantar keratoderma, typically associated with a P25L KRT5 mutation. In this report, we present the case of a 77‐year‐old woman with a history of palmoplantar keratoderma who developed a transient EBS‐MP‐like phenotype associated with bexarotene treatment for cutaneous T‐cell lymphoma. Genetic sequencing revealed a heterozygous G138E KRT5 variant, present in approximately 10% of the European population and only rarely associated with pathology. Bexarotene, which has been reported to alter keratin synthesis, caused vesiculobullous reactions with similar frequency in clinical trials. We propose that the cumulative effect of drug treatment and underlying G138E polymorphism resulted in transient basal keratinocyte lysis in our patient and provides a plausible explanation for this unusual bexarotene side effect.

Papular eruption associated with palifermin

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