Both primary and
metastatic melanoma of the gallbladder are rare.
malignant melanoma of the gall bladder is difficult or impossible to
distinguish from secondary melanoma.
To help in the
differentiation between primary and secondary malignant melanoma in
the gall bladder and to overcome some of the difficulties posed by the
clinical identification of what is often a small or relatively
inaccessible primary tumour, it is suggested that certain criteria
should be fulfilled before primary melanoma is diagnosed -
(i) Tumours must
be solitary and arise from the mucosal surface of the gall bladder;
(ii) they must
either be papillary or polypoid;
(iii) they must
either display junctional activity or have any other primary sites
excluded by history taking, examination, and investigation.
examination reveal mostly spindle cells with vesicular nuclei and
Many cells stained positively for S 100 protein and HMB 45 using immunohistochemistry and they contained dark brown
pigment that stained as melanin pigment with Fontana-Masson.
The tumour may
metastasize to the common bile duct, stomach, the duodenum, the
jejunum, the lung, the brain and a bronchopulmonary lymph node.
Melanoma of the Gallbladder