Table 2.
Immunohistochemical and molecular findings of all four cases
| Case | Immunohistochemistry | Molecular testing | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Melan A | HMB-45 | ALK, ROS, NTRK | BRAF (V600E) | p16 | p21 | Proliferation fraction | BAP1 | TCP | MAP2K1 mutation - allele frequency | CNVs | ||
| 1 | Positive | Weakly positive superficially | Negative | - | Few positive cells (checkerboard pattern) | Positive | Low (around 2%) | Positive | 30–50% | c.306_311del (p.Ile103_Lys104del) - 13% | 4a |
Partial loss 2p Partial loss and partial CN-LOH 19p Chromothripsis 22q |
| 2 | Positive | Positive (slightly less staining deeper) | Negative | Negative | Negative (in majority of cells) | Positive (mainly at junction) | Low | Positive | 30% | c.307_312del (p.Ile103_Lys104del) - 24% | 6 |
Monosomy 9 Gain 6p Partial loss 6q Monosomy 10, 12, 19 |
| 3 | Positive | Positive (partly maintained deeper) | Negative | - | Positive (checkerboard pattern) | Negative | - | - | 10–20% | c.169A>G (p.Lys57Glu) - 7% | 0 | Probably not reliable due to low TCP |
| 4 | Positive | Negative | Negative | - | Focally positive | Positive | Very low | - | 60% | c.306_311del (p.Ile103_Lys104del) - 28% | 6 | Trisomy chromosomes 5, 6, 11, 14, 15, and 20b |
aChromothripsis of chromosome 22 was counted as 1 CNV
bDue to poor quality of the SNP array, presence of other CNVs could not be excluded completely
CN-LOH, copy neutral loss of heterozygosity; CNVs, copy number variations; TCP, tumor cell percentage