Neutrophilic eccrine hidradenitis (NEH) is a rare, self-limited hypersensitivity disorder characterized by toxic injury to eccrine coils. While its pathophysiology is poorly understood, it is thought that direct cytotoxic injury from an exogenous trigger precipitates the recruitment of neutrophils as a reactive process.

NEH is most frequently associated with chemotherapy, particularly cytarabine, but also with bleomycin, cyclophosphamide, anthracyclines, decitabine, BRAF inhibitors (eg, dabrafenib and vemurafenib), cetuximab, dasatinib, 5-fluorouracil, and methotrexate, among other agents. It typically occurs 7-14 days after initiation of the drug. However, the range of onset is broad, occurring anywhere from 2 days to 2 years after chemotherapy initiation. Patients may experience recurrences with subsequent courses of chemotherapy.

Other associated causes:

• Other medications: acetaminophen, carbamazepine, minocycline, adalimumab, and granulocyte colony-stimulating factor (G-CSF)
• Paraneoplastic phenomenon: reported with myeloproliferative (eg, acute myeloid leukemia) and lymphoproliferative (eg, Hodgkin lymphoma) malignancies as well as solid organ malignancies such as osteosarcoma, testicular carcinoma, metastatic breast cancer, and Wilms tumor) without preceding chemotherapy
• HIV
• Bacterial infections (Serratia, Staphylococcus, Enterobacter, and Nocardia).
• Behçet disease
• Rarely, heat damage from high environmental temperatures (in the pediatric population)
• Idiopathic (otherwise healthy individuals)

While pain is the most commonly reported symptom, up to half of patients may be asymptomatic, and NEH may sometimes be pruritic. The dermatologic manifestations may be accompanied by fever and neutropenia. Lesions are usually self-limited but may recur with subsequent drug exposure.