Case 100 - Discussion
Uploaded: 2007-09-27, Updated: 2007-09-27
HMB45: NEGATIVE S100: TUMOR IS INDETERMINATE. MITF: NEGATIVE. MART-1: NEGATIVE. VIMENTIN:: TUMOR IS POSITIVE. TTF-1: TUMOR IS NEGATIVE. CK5/6: TUMOR IS NEGATIVE. CK20: TUMOR IS NEGATIVE. CK7: TUMOR IS NEGATIVE. CD117: NEGATIVE. CD30: NEGATIVE. LCA: NEGATIVE. CD3: NEGATIVE. CK19: NEGATIVE AFP: NEGATIVE. AE 1/3: NEGATIVE. CK8/18: POSITIVE.
Ultrastructurally, considerable fixation and processing artifact is
apparent. However, the neoplasm consists of sheets of epithelioid
like cells in close approximation with each other. Numerous tight
junctions are identified. However, the fine architecture of plasma
membranes have been destroyed by the paraffin embedding process. The
cells appear to have abundant endoplasmic reticulum and throughout
these cells there are poorly defined electron dense structures that
are the size of melanosomes. These structures lack the unit membrane
surrounding them probably because of the fixation artifact. In
several of these, there is some suggestion of intercrystalline
structure. No villi formation is noted. No glandular formation is
noted. (Interpretation performed by Dr. WJH. Performed in the
Electron Microscopy Laboratory, Creighton Medical Laboratories,
ULTRASTRUCTURAL IMPRESSION: Undifferentiated malignant neoplasm with electron dense core structures, suggestive of melanosomes.
COMMENT: The ultrastructural finding suggests that the primary for this neoplasm is a melanoma.