The usefulness of tyrosinase in the immunohistochemical assessment of melanocytic lesions: a comparison of the novel T311 antibody (anti-tyrosinase) with S-100, HMB45, and A103 (anti-melan-A)

Abstract

Aim-To compare the sensitivity and staining pattern of the new immunohistochemical antibody to tyrosinase (T311) with S-100, HMB45, and the recently evaluated antibody to melan-A (A103) in a range of melanocytic lesions. Method-Archival, formalin fixed, paraffin wax embedded sections from 50 benign and malignant melanocytic lesions were stained immunohistochemically with anti-tyrosinase, A103, S-100, and HMB45. They were scored semiquantitatively for the distribution and intensity of staining. Results-All melanomas, with the exception of desmoplastic melanoma, showed some staining with all four antibodies. Overall, T311 and A103 showed an intermediate sensitivity compared with that of S-100 and HMB45. T311 stained most benign and malignant lesions strongly and diVusely with minimal background staining. Immunoreactivity was found to be patchy in some naevi, with weak or absent staining of the mature melanocytes. A103 showed strong and diVuse staining of all benign lesions and most melanomas with minimal background staining. S-100 was the most sensitive, with diVuse staining of most lesions, including desmoplastic and metastatic melanoma, but lacked specificity. HMB45 was the least sensitive antibody, frequently demonstrating patchy staining with absent staining in some benign naevi. Conclusions-S-100 remains the most sensitive marker of melanocytes. However, because of its lack of specificity, it should be used with at least one other more specific antibody. HMB45 is more specific, but lacks sensitivity; T311 is a reliable marker of melanocytes in paraYn wax embedded sections and is worth consideration for use in a staining panel, although it shows no additional benefit over A103.

Semaphorin 3F, a chemorepulsant for endothelial cells, induces a poorly vascularized, encapsulated, nonmetastatic tumor phenotype

“…SM cells were used for several reasons: (a) of any cell line examined, SM cells express the highest levels of NRP2, the functional receptor of SEMA3F; (b) SM cells constitute an excellent human tumor model system in nude mice, because they can be injected orthotopically into the skin with 100% tumor take, and tumor volume can be measured externally and (c) SM cells metastasize spontaneously and reproducibly to regional lymph nodes and lungs in nude mice. Large metastases can be seen visually, and even though these melanomas are amelanotic, the disseminated micrometastases can be detected by histological staining with melanoma-specific antibodies such as S100β or HMB45 (35). A thorough analysis was performed to look for metastases, including sectioning of the tissues at multiple levels, staining by standard H&E, staining with specific melanoma markers, and culturing of minced lung pieces to observe any melanoma cell outgrowth.…”

Pathology of Liver Metastases

“…33 However, S100 remains the most sensitive for detection of melanoma, although it lacks specificity. 34 …”

Immunohistochemical characteristics of melanoma

“…5,11 The reported sensitivity of HMB45 for melanoma ranges from 69% to 93%, 5,6,[11][12][13][14][15][16][17] and expression is maximal in primary melanoma specimens (77-100%) and less in metastases (58-83%). 6,[11][12][13][14][15][16][17] Staining may be patchy, and melanoma cells are less diffusely positive than with other markers. 11,14,15,17 There may be strong staining with HMB45 in the epidermal component of a primary melanomas with gradually weaker staining in the deeper vertical growth phase.…”

“…6,[11][12][13][14][15][16][17] Staining may be patchy, and melanoma cells are less diffusely positive than with other markers. 11,14,15,17 There may be strong staining with HMB45 in the epidermal component of a primary melanomas with gradually weaker staining in the deeper vertical growth phase. 5,6,14 ( Figure 1) There is some dispute as to whether HMB45 is less sensitive in amelanotic melanomas.…”