Diagnostic Utility of Neural Stem and Progenitor Cell Markers Nestin and SOX2 in Distinguishing Nodal Melanocytic Nevi From Metastatic Melanomas

Pei-Ling Chen; Wei-Shen Chen; Jianping Li; Anne C Lind; Dongsi Lu

Disclosures

Mod Pathol. 2013;26(1):44-53. 

In This Article

Results

Nestin Expression in Lymph Nodes With Metastatic Melanoma

All 23 cases of metastatic melanoma harbored intra-parenchymal tumor cells that were epithelioid and/or spindled in morphology and showed cytological features of malignancy (marked atypia, mitoses, etc). Some tumor cells contained melanin pigment, whereas some were amelanotic.

Immunostain for nestin revealed strong (3+) and diffuse cytoplasmic positivity in 18 lymph nodes (n=18/23, 78%; Figure 1a-c). Expression of nestin in rare cells with strong (3+) cytoplasmic positivity was seen in 4 lymph nodes (n=4/23, 17%), whereas 1 lymph node showed diffuse, weak (1+) positivity (n=1/23, 4%). If all tumor cells with strong (3+) nestin immunostain were considered positive, the sensitivity of nestin in detecting metastatic melanoma was 96% ( Table 2 ). Interestingly, nestin was consistently expressed in metastatic melanomas with spindle cell morphology, highlighting >85% of these tumors' cells (Figure 1a-c). In metastatic melanomas with epithelioid morphology, the melanin-producing tumor cells showed decreased nestin staining (Figure 2a-b) compared with the amelanotic tumor cells. However, within the melanotic tumor foci, scattered tumor cells with strong (3+) nestin staining were readily identifiable. Overall, nestin immunostain was highly sensitive for metastatic melanomas, especially in spindle and amelanotic tumor cells.

Figure 1.

(a) Metastatic melanoma (MetM) in lymph node, hematoxylin and eosin (H&E; × 6.7 magnification). (b) H&E ( × 100 magnification). (c) Nestin strongly (3+) and diffusely highlights MetM ( × 100 magnification).

Figure 2.

(a) Pigment-producing epithelioid melanoma cells, hematoxylin and eosin ( × 100 magnification). (b) Nestin expression is decreased in the pigment-producing tumor cells compared to the amelanotic tumor cells ( × 100 magnification).

SOX2 Expression in Lymph Nodes With Metastatic Melanoma

Nuclear SOX2 staining was positive in 13 of 23 metastatic melanomas (n=13/23, 57%; Figure 3a-c; Table 2 ). However, no significant difference in SOX2 staining was observed between the spindle and epithelioid tumor cells (both melanotic and amelanotic). Overall, the sensitivity of SOX2 in detecting metastatic melanoma in lymph nodes was somewhat lower compared with nestin.

Figure 3.

(a) Metastatic melanoma (MetM) in lymph node, hematoxylin and eosin (H&E; × 50 magnification). (b) H&E ( × 200 magnification). (c) MetM is positive for nuclear SOX2 ( × 200 magnification).

Nestin Expression in Nodal Melanocytic Nevi

For nodal melanocytic nevi (n=17), the melanocytic foci were either capsular or trabecular in location. Fifteen nodal nevi showed no nestin expression (n=15/17, 88%) and 2 contained rare cells with weak (1+)/blush-like positivity (n=2/17, 12%; Figure 4a-b and Table 3 ). One of these two lymph nodes was from a patient with no history of melanoma, and the other was from a patient with a history of melanoma. Overall, nestin staining was negative in the majority of nodal melanocytic nevi (88%) and strongly positive in metastatic melanomas (96%; P<0.001).

Figure 4.

(a) Nodal melanocytic nevus (nMN), hematoxylin and eosin (H&E; × 100 magnification). (b) Nestin is negative in nMN ( × 100 magnification). (c) Another nMN, H&E ( × 100 magnification). (d) SOX2 is negative in nMN ( × 100 magnification).

SOX2 Expression in Nodal Melanocytic Nevi

Nuclear SOX2 expression was negative in 13 nodal nevi (n= 13/16, 81%) (Figure 4c–d) and positive in 3 nodal nevi (n= 3/16, 19%; Table 3 ). The three cases that were positive for SOX2 were not the same nodal nevi that demonstrated weak 1+ nestin staining. Overall, SOX2 was negative in the majority of nodal nevi (81%) and positive in 57% of metastatic melanomas (P=0.02).

Nestin and SOX2 Expression in Nodal 'Subcapsular/Intranodal Melanocytic Rest'

One case that was originally diagnosed as 'subcapsular/intranodal melanocytic rest' was included in this study. The patient had a history of malignant melanoma, but histological sections of the primary tumor could not be obtained for comparison at the time of lymph node evaluation. The melanocytes within the subcapsular/intranodal melanocytic rest, some of which were pigmented, appeared bland and had smooth nuclear contours and inconspicuous nucleoli. A diagnosis of nevus aggregate was thus favored (Figure 5a).

Figure 5.

(a) 'Subcapsular/intranodal melanocytic rest' with bland cytology, hematoxylin and eosin ( × 141 magnification). (b) Subsets of cells with strong (3+) Nestin positivity ( × 141 magnification). (c) SOX2 is negative ( × 141 magnification).

Immunostain for nestin showed subsets of cells with strong (3+) nestin positivity in this melanocytic aggregate (Figure 5b). Compared with what we observed in other nodal melanocytic nevi, strong nestin expression was unusual for terminally differentiated nevocytes. Careful inspection of the nuclei showed no SOX2 expression (Figure 5c). Upon re-examining the original H&E-stained sections, the melanocytes appeared larger than what would be expected of a typical nevus, and the nuclei were also larger. Review of the patient's electronic medical record revealed metastatic melanoma to the same lymph node region 2 years later. Retrospectively, this lymph node likely harbored metastatic melanoma rather than a nodal melanocytic nevus.

Metastatic Desmoplastic Melanoma to the Lymph Node

Desmoplastic melanoma is a rare variant of malignant melanoma that is typically negative, or at best focally positive, for melan-A and HMB-45.[12] As such, S100 protein is one of the most commonly applied marker for this tumor. A rare case of metastatic, melan-A-negative desmoplastic melanoma was identified in our database and included in this study (Figure 6a-b and e). The lymph node showed nests of spindled tumor cells infiltrating the nodal parenchyma from the periphery of the lymph node. Nestin strongly highlighted the tumor cells (Figure 6c), and SOX2 nuclear staining was also positive (Figure 6d). Both markers highlighted the tumor cells with high sensitivity, but not the background follicular dendritic cells, as observed with S100 protein immunostain (Figure 6f).

Figure 6.

(a) Metastatic desmoplastic melanoma infiltrating from the periphery of the lymph node, hematoxylin and eosin (H&E; × 40 magnification). (b) H&E ( × 200 magnification). (c) Nestin strongly (3+) highlighted the tumor cells ( × 200 magnification), and (d) SOX2 nuclear staining was also positive ( × 200 magnification). (e) Melan-A is negative in the metastatic melanoma cells. (f) S100 protein highlights both desmoplastic melanoma and follicular dendritic cells ( × 200 magnification).

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