Unicentric Castleman's disease imitating metastatic melanoma: A case report

This case report shows a unique case of Castleman's disease in the context of histopathological diagnosis of cutaneous melanoma where clinical and radiological features of Castleman's disease were masked by presumptive diagnosis of metastatic melanoma. The disease is part of a group of lymphoproliferative disorders with characteristic histopathological features that can occur in any lymph node in the body, characterised by slow growing painless masses which are asymptomatic until mass effect occurs. This case highlights the need for caution when considering management of lymphadenopathy with clinically/radiologically suspicious nodes.

A 65 year old man with metastatic melanoma of the left elbow presented for axillary sentinel node mapping and was found to have a hypoechoic enlarged node on ultrasound. This was further investigated and found to be a lymphoproliferative growth pathognomonic for Castlemans disease.

Whilst clinically detected lymphadenopathy in the draining node basin of a primary cutaneous melanoma is highly suspicious for nodal metastasis, it is sometimes not possible to confirm or exclude this diagnosis without complete histological examination of the node. Multidisciplinary input from the surgeon, histopathologist and radiologist is a key step in confirming diagnosis.

Alternative diagnoses must be considered in the context of lymphadenopathy, even in the context of malignant melanoma.