Solitary plaque on the scalp as a primary manifestation of Hodgkin lymphoma: a case report and review of the literature.

Cutaneous Hodgkin lymphoma is infrequent and typically occurs after extensive involvement of the lymph nodes. The condition decreased significantly in incidence in the past two decades, likely owing to the new treatment protocols composed of chemotherapy, radiotherapy and stem cell transplantation. Nevertheless, recognition of this uncommon but significant disease manifestation is important from a prognostic and therapeutic perspective. We are sharing a recent case of Hodgkin lymphoma where the primary presentation appeared as a solitary plaque on the left side of the occipital scalp, clinically suspected to represent a ruptured follicular cyst. The patient underwent excisional biopsy. Histological assessment revealed Hodgkin lymphoma affecting the skin. Radiological studies showed no regional lymphadenopathy. However, two enlarged lymph nodes were identified in the mediastinum and were positron emission tomography avid. The patient underwent systemic treatment without further histopathological examination of these two lymph nodes. Not being clear if these enlarged two lymph nodes were related to his cutaneous disease or not, we cannot be sure if the patient was afflicted either by primary cutaneous Hodgkin lymphoma or by secondary cutaneous involvement because of hematogenous spread. In either case, primary or secondary cutaneous Hodgkin disease is an extreme rarity. The literature is critically reviewed.