Table 3.

Histological diagnosis and immunohistochemical (IHC) markers in the diagnosis of brain metastases from cancer of unknown primary (BM-CUP).

Studies	Histological Diagnosis	Immuno-Histochemical Markers Used	Confirmed Primaries at Follow-Up
Matsunaga et al., 2019 [27]	42 Adeno-K, 4 squamous-cells, 2 neuroendocrine	NS	NS
Mavrakis et al., 2005 [6]	7 Adeno-K, 2 poorly differentiated malignant epithelial tumours	NS	2/9 (22%)
Drlicek et al., 2004 [39]	Lung 5, colorectum 1, breast 1, kidney 1	CK (AE1/AE3, 7, 10/13, 18, 20), vimentin, protein S100, TTF-1, and CA 15-3, 19.9, 125, PSA	0
Bartelt and Lutterbach, 2003 [14]	15 Lung Adeno-K,4 Squamous-cells, 4 Large-cells, 4 Small-cells, 20 Other	NS	NS
Klee et al., 2002 [60]	14 Adeno-K (12 CK 7 +, none CK 20), 1 carcinoma (no CK 7, CK 20 and CK), 1 melanoma	CK7, CK20, PSA, HCG, CA125 and “antibodies indicating breast or pulmonary primary”	7/14 (50%)
Rudà et al., 2001 [61]	4 Lung Adeno-K, 1 Squamous-cells, 3 Colon Adeno-K, 1 Pancreatic Adeno-K, 18 no diagnosis	NS	27/33 (81%)
Maesawa et al., 2000 [17]	10 Adeno-K, 2 Squamous-cells, 1 Clear-cells, 2 Undifferentiated	NS	4/15 (26.7%)
Nguyen et al., 1998 [18]	31 Adeno-K, 2 small-cells,1 squamous-cells, 4 other, 1 missing	NS	12/39 (31%)
Salvati et al., 1995 [10]	65 Adeno-K, 10 Squamous-cells, 10 Melanoma, 7 Undifferentiated, 7 other small-cells	NS	64/100 (64%)
Debevec, 1990 [44]	Anaplastic K and adeno-K were most frequent	NS	47/75 (63%)
Merchut, 1989 [7]	8 Adeno-K + 1 squamous-cells	NS	47/56 (84%)
Chee and Byrnes, 1988 [4]	5 Adeno-K, 3 anaplastic, 4 squamous-cells, 1 sarcoma, 1 transitional-cells	NS	35/51 (68%)
Eapen et al., 1988 [23]	9 No diagnosis, 19 Adeno-K, 7 Squamous K, 5 Anaplastic K, 1 large-cells, 1 small-cells, 1 transitional-cells	NS	11/43 (25%)
Zimm et al., 1981 [28]	14 Adeno-K, 2 squamous	NS	10/16 (37%)

NS = not specified, IHC = immunohistochemistry, K = carcinoma, Adeno-K = adenocarcinoma.