Metastatic melanoma to kidney

Case contributed by Dr Andrew Ryan


History of removal of melanoma forehead with multiple recurrences. Now presents with flank pain.

Patient Data

Age: 50
Gender: Female


Coronal section of the right kidney ('bi-valved') with relatively circumscribed, firm, pale tan to grey tumour, 68 x 48 x 48mm, in the mid-cortex. The tumour distorts the capsule but does not breach it and does not involve the perinephric fat.

Micro (medium power): The tumour is relatively undifferentiated and was initially labelled a 'malignant spindled cell tumour' favouring metastatic melanoma (given the strong family history). 

Micro (high power): The spindled cells show no residual differentiation, including no evidence of residual cytoplasmic pigmentation. 

Case Discussion

Tumours such as this, with no morphological clues to indicate the cell lineage, are often initially labelled as 'malignant spindled cell tumour'; examples of what a pathologist looks for include residual gland, mucin or keratin production (poorly differentiated carcinoma), melanin pigmentation (melanoma) or specific mesenchymal differentiation (e.g. rhabdomyoblasts, lipoblasts). When these morphological clues are not present, we attempt to uncover residual protein expression (immunohistochemistry), utilise cytogenetic profiling, or sometimes even resort to ultrastructural morphology (electron microscopy). In this case, the immunohistochemical tests confirmed metastatic melanoma.

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Case information

rID: 16176
Case created: 27th Dec 2011
Last edited: 10th Apr 2018
Inclusion in quiz mode: Excluded

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