Neutrophilic Dermatoses: a Clinical Update.

Purpose of Review: Neutrophilic dermatoses are defined by the presence of a sterile neutrophilic infiltrate on histopathology. This review focuses on the pathogenesis, epidemiology, clinicopathological features, diagnosis, and management of four disorders: Sweet syndrome, pyoderma gangrenosum, Behçet syndrome, and neutrophilic eccrine hidradenitis. Recent Findings: Recent studies have provided insight into the complex pathogenesis of neutrophilic dermatoses. Evidence supports an intricate interplay of abnormal neutrophil function and inflammasome activation, malignant transformation into dermal infiltrating neutrophils, and genetic predisposition. Summary: Neutrophilic dermatoses have diverse cutaneous and extracutaneous manifestations and may be associated with significant morbidity and mortality. Common underlying associations include infectious, inflammatory, and neoplastic disorders, as well as drug reactions. Emerging diagnostic and therapeutic frameworks identify an expanding role for biologic and targeted anti-inflammatory therapies.

Metastatic squamous cell carcinoma presenting as an erythematous nodule in a man with lung adenocarcinoma.

Skin metastases from visceral malignancies have been well documented in the literature, and may be the presenting sign of an occult internal malignancy. Lung cancer in particular is a relatively common cause of skin metastases, which are considered a poor prognostic sign. Rarely, patients with lung cancer develop a second primary lung cancer that may require a novel chemotherapeutic regimen. The frequency of second primary malignancies presenting with metastatic skin lesions is not documented in the literature. We present a case of a 50-year-old man with a history of metastatic lung adenocarcinoma who was referred for evaluation of a nodule overlying his right mandible, which had been progressively enlarging for two weeks. Biopsy demonstrated metastatic squamous cell carcinoma. Subsequent CT-guided biopsy of a left retroperitoneal lymph node was conducted and notable for squamous cell carcinoma. Therefore, this patient's skin lesion was the presenting sign of a second primary visceral tumor, likely originating in the lung. We present this case to raise clinical awareness of the rare phenomenon that cutaneous metastasis may be the first sign of a visceral cancer, even in the setting of a previous distinct primary malignancy.

Steatocystoma.

Steatocystoma multiplex is a rare condition that is characterized by cutaneous cysts and may be inherited in an autosomal dominant manner or may occur sporadically. The pathogenesis is hypothesized to involve mutations in the keratin 17 gene. There are no internal manifestations. The lesions are usually asymptomatic. However, a suppurative variant exists in which the lesions become inflamed and suppurative after minor trauma. Treatments include cryosurgery, aspiration, surgical excision, laser therapy, and modified surgical incision techniques. This report presents a case of steatocystoma multiplex, the suppurative variant, in a 26-year-old woman with involvement of rare locations on the buttocks, groin, and extremities.