Metastatic malignant melanoma of unknown primary site to the brain: A case report

Abstract

Introduction and importance: The natural history of metastatic melanoma in the absence of a known primary site has been poorly defined. The disease usually presents a significant cause of morbidity and mortality. Around 90% of melanomas have cutaneous origin, but still there are melanomas that could be found in visceral organs or lymph nodes with unknown primary site. Spontaneous regression of the primary site could be an explanation. The disease is frequently diagnosed after treatment for known extracranial metastases and has a poor outcome despite various local and systemic therapeutic approaches.

Case presentation: Herein, we present a case of a 43-year old female presented with history of headaches and enlarged a left inguinal lymph node. Notably, no cutaneous lesions could be identified by history or on physical examination. CT-scan of the brain revealed a space occupying lesion and the inguinal lymph node biopsy confirmed the diagnosis of metastatic malignant melanoma. The patient succumbed shortly after establishment of diagnosis.

Clinical discussion: Most patients with brain metastases from malignant melanoma are diagnosed after treatment for known extracranial metastases and have a poor outcome despite various local and systemic therapeutic approaches.

Conclusion: Metastatic melanomas of brain with unknown primary present a significant morbidity and mortality and confer a poor prognosis. Delay in diagnosis and treatment is of serious concern when it comes to improve the prognosis of patients with this disease. The optimal treatment depends on the objective situation, often surgery, radiosurgery, whole brain radiotherapy and chemotherapy can be used in combination to obtain longer remissions and optimal symptom relieve.

Keywords: Brain; Inguinal lymph node; Malignant melanoma; Metastasis; Unknown primary.

Fig. 1

Axial CT pelvis showing an enlarged matted and necrotic lymph nodes in the left superficial femoral region suggestive of metastatic lymphadenopathy.

Fig. 2

Axial CT brain shows three hyperdense masses in the right lentiform nucleus (1.8 cm × 1.6 cm), left parietal lobe (1.5 cm × 1.1 cm) and left occipital lobe (1.7 cm × 1.7 cm) with surrounding perilesional oedema; effacement of the right lateral ventricle seen with 0.6 cm midline shift towards the left side the features suggestive cerebral metastasis.

Fig. 3

Histopathology of the inguinal lymph node demonstrating a complete effacement of the nodal architecture and replaced by a tumor whose cells were hyperchromatic, epithelioid and spindled shaped and the presence of brown pigmentation, H & E staining, ×100 original magnification. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 4

Photomicroscopy demonstrating strong immune reactive of the tumor cells with HMB-45, IHC ×200 original magnification.