Jose A. Plaza

Correlation between KIT expression and KIT mutation in melanoma: a study of 173 cases with emphasis on the acral-lentiginous/mucosal type

The role of immunohistochemistry in the assessment of KIT status in melanomas, especially acral lentiginous/mucosal, is not well established. Although the reported prevalence of KIT mutations in acral lentiginous/mucosal melanomas is relatively low, detection of mutations in KIT can have profound therapeutic implications. We evaluated the efficacy of immunohistochemistry to predict mutations in KIT. One hundred seventy-three tumors, comprising primary and metastatic melanomas (141 acral lentiginous/mucosal, 5 nodular, 4 lentigo maligna, 3 superficial spreading, 2 uveal, 1 melanoma of soft parts, 8 metastases from unclassified primaries, and 9 metastases from unknown primaries) were studied. Immunohistochemical expression of KIT using an anti-CD117 antibody and KIT mutational analysis by gene sequencing of exons 11, 13, and 17 were performed. Eighty-one percent of acral lentiginous/mucosal melanomas, primary and metastatic, showed KIT expression by at least 5% of the tumor cells. The overall frequency of activating KIT gene mutations in acral lentiginous/mucosal melanomas was 15% (14 out of 91 cases), being the L576P mutation in exon 11 the most frequently detected (4 of 14 cases). Cases showing less than 10% positive tumor cells were negative for KIT mutations. Eighty-two percent (12 of 14) of cases positive for KIT mutation showed KIT expression in more than 50% of the cells. An association between immunohistochemical expression of KIT and mutation status was found (P=0.007). Immunohistochemical expression of KIT in less than 10% of the cells of the invasive component of acral lentiginous/mucosal melanomas appears to be a strong negative predictor of KIT mutation and therefore can potentially be used to triage cases for additional KIT genotyping.

Value of p63 and podoplanin (D2-40) immunoreactivity in the distinction between primary cutaneous tumors and adenocarcinomas metastatic to the skin: a clinicopathologic and immunohistochemical study of 79 cases

The distinction of metastatic carcinomas to the skin from poorly differentiated primary cutaneous carcinomas and sometimes primary benign adnexal tumors can pose a significant diagnostic challenge. The purpose of this study was to evaluate the role of p63 and podoplanin (D2‐40) immunoreactivity for separating primary skin tumors vs. cutaneous metastases of carcinomas from internal organs. Thirty seven primary tumors and 42 cutaneous metastatic adenocarcinomas were evaluated. The 37 primary cutaneous tumors included 14 cases of benign adnexal tumors, 9 malignant skin adnexal neoplasms, and 14 primary squamous and basal cell carcinomas. The 42 metastatic adenocarcinomas all corresponded to metastases from patients with a well‐documented history of a primary tumor at another location. We found variable positivity with podoplanin in all primary cutaneous neoplasms including spiradenoma (6/6), hidradenoma (2/4), cylindroma (3/3), desmoplastic trichilemmoma (1/1), poorly differentiated squamous cell carcinoma (4/4), sebaceous carcinoma (1/1), basal cell carcinoma (4/10), trichilemmal carcinoma (2/2), eccrine carcinoma (3/3), microcystic adnexal carcinoma (1/1), adnexal carcinoma NOS (1/1), and porocarcinoma (1/1). In contrast, all metastatic carcinomas were negative (0/42) for podoplanin. In regards to p63, all cases of primary cutaneous tumors were positive for p63 (37/37); in contrast, all cutaneous metastatic carcinomas were negative (0/42). Sensitivity, specificity, and positive and negative predictive values of podoplanin and p63 immunoreactivity to separate primary skin neoplasms from metastatic carcinomas were 78.4, 100.0, 100.0 and 84.0% for podoplanin, respectively, and 100.0, 100.0, 100.0 and 100.0% for p63, respectively. The differences in p63 and podoplanin immunohistochemical expression between primary skin tumors and metastatic carcinomas to the skin were statistically significant (p < 0, 0001). The results of our study suggest that the combined expression of p63 and podoplanin are a useful adjunct for the diagnosis of skin tumors in the clinical setting of a questionable metastasis and may be relatively specific for distinguishing primary skin tumors from metastatic carcinomas to the skin.

HER-2/neu expression in extramammary Paget disease: a clinicopathologic and immunohistochemistry study of 47 cases with and without underlying malignancy.

Extramammary Paget disease (EMPD) is an infrequent skin cancer sometimes representing a secondary event caused by extension of an underlying carcinoma. Her‐2/neu overexpression in breast cancer is correlated with a more aggressive behavior, but anti‐Her‐2/neu therapy improves survival in these patients. We investigated Her‐2/neu expression by immunohistochemistry in cases of EMPD with and without underlying malignancy to try to correlate with tumor recurrence, progression and possible targeted therapy. Forty‐seven cases were analyzed (6 from the scrotum, 7 perianal region, 1 axilla and 33 vulva). Two cases had invasive EMPD (one from vulva and one from scrotum). The overall Her‐2/neu expression was 31.9%. Of the noninvasive EMPD of the vulva (32 cases), Her‐2/neu was shown in 38%. The case of invasive vulvar EMPD was negative. All six scrotal EMPD lacked Her2/neu expression. Her‐2/neu was expressed in two of seven perianal cases (33.3%). The EMPD on the axilla (one case) was negative. Eighteen cases had recurrence, and of these, 44.4% expressed Her‐2/neu in the initial lesion. A high proportion of EMPD showed Her‐2/neu expression (31.9%), indicating that these patients may benefit from targeted therapy. The proportion of positive cases was higher in lesions that had recurred at last follow up (44.4%), suggesting a more aggressive behavior.

Assessment of TCR‐β clonality in a diverse group of cutaneous T‐Cell infiltrates

While some unequivocally benign infiltrates are easy to distinguish from cutaneous T‐cell lymphoma (CTCL), drug‐associated lymphomatoid hypersensitivity reaction and cutaneous lesions of collagen vascular disease can show cytologic atypia, clonality and an immunophenotypic profile that closely simulates CTCL and cause diagnostics difficulties. Similar immunophenotypic and molecular abnormalities to those of malignant lymphoma can also be observed in pityriasis lichenoides chronica (PLC), large plaque parapsoriasis (LPP), pigmented purpuric dermatosis (PPD) and atypical lymphocytic lobular panniculitis leading one to consider these entities as forms of cutaneous lymphoid dyscrasia. The purpose of our study was to evaluate the distinction of these various subcategories of cutaneous T‐cell infiltrates by assessment of T‐cell receptor (TCR)‐β gene rearrangement. Formalin‐fixed paraffin‐embedded skin biopsies from 80 patients containing a T‐cell dominant lymphocytic infiltrate were analyzed for TCR‐β gene rearrangement. Our findings indicate that monoclonality is a reliable characteristic of CTCL with polyclonality being very infrequent. However, some cases of drug associated lymphomatoid hypersensitivity, collagen vascular disease and the various cutaneous lymphoid dyscrasias (i.e. PLC, PPD and atypical lymphocytic lobular panniculitis) could manifest restricted molecular profiles in the context of an oligoclonal process or frank monoclonality.

Sclerosing paraganglioma: report of 19 cases of an unusual variant of neuroendocrine tumor that may be mistaken for an aggressive malignant neoplasm.

Nineteen cases of a distinctive variant of paraganglioma characterized by extensive collagen deposition resulting in a pattern of growth that resembled an invasive malignant neoplasm are described. The patients were 3 men and 16 women, 32 to 69 years of age (mean, 50.5 years). The tumors were located in the carotid body region, parapharyngeal region, and mediastinum. Tumor size ranged from 2 to 6 cm in greatest diameter. Grossly, the tumors were described as rubbery to firm, tan-red, and with extensive areas of sclerosis. Histologic examination showed nests and cords of tumor cells separated by broad bands of fibrous tissue. The tumor cells ranged from round to polygonal with abundant cytoplasm to elongated spindle cells with scant cytoplasm. Nuclear cytomegaly was present focally enhancing the atypical appearance of the tumor cell population in 17 cases. Mitoses were sparse (<1 × 10 HPF), and there was no evidence of necrosis in any of the cases. Foci of vascular and perineural invasion were present in 2 and 4 cases, respectively. The most striking morphologic feature was the presence of irregular cords and bands of hyalinized fibrous tissue that compartmentalized the lesion into irregular nests, islands, or cords of tumor cells, imparting them with an infiltrative appearance. All the tumors showed positive immunostaining for chromogranin, synaptophysin, and monoclonal neuron specific enolase. S-100 protein stains identified a sustentacular cell network, whereas cytokeratin AE1/AE3 was negative in all cases. Clinical follow-up in 14 cases, ranging from 2 months to 20 years (mean follow-up, 6.6 years) showed evidence of local recurrence in 2 cases and the development of a separate tumor in the contralateral neck in 1 case. The remainder of patients were free of recurrence or metastasis following simple local excision. Because of the prominent sclerosis, a diagnosis of an invasive malignant neoplasm was initially considered in the majority of cases. Sclerosing paraganglioma should be included in the differential diagnosis of sclerosing lesions of the head and neck region and mediastinum. Appropriate immunohistochemical stains may be of aid for establishing the correct diagnosis.

Depletion of M2-like tumor-associated macrophages delays cutaneous T-cell lymphoma development in vivo.

Macrophages have key roles in tumor development and invasion in several human cancers, but little is known about their pathogenic role in cutaneous T-cell lymphoma (CTCL). Herein, we used PCR arrays to profile the expression of inflammatory cytokines in 12 patients with mycosis fungoides (MF), the most common variant of CTCL. Compared with normal controls, MF skin displayed increased mRNA levels of macrophage-related cytokines. Moreover, we detected CD163, a reliable marker of tumor-associated macrophages, in the tumor microenvironment of MF biopsies. To demonstrate that macrophages had a role in CTCL tumorigenesis, we xenografted human CTCL tumor cells in immunocompromised mice and compared tumor development using clodronate-containing liposomes to deplete macrophages in mice. Mice treated with clodronate-containing liposomes show markedly less tumor growth compared with mice treated with phosphate-buffered saline-containing liposomes (P<0.001). We also noted a strong correlation between macrophage depletion and decreased expression of vascular marker, CD31, and lymphatic marker, podoplanin, suggesting a role for macrophages in angiogenesis. In vitro, clodronate-containing liposomes killed activated murine M2 macrophages, but not Hut78 cells, demonstrating selective ability to induce apoptosis in macrophages. Our data indicate that macrophages have a critical role in the progression of Hut78 cell tumor formation in skin, thus providing a new therapeutic strategy for CTCL.

Cutaneous metastases of malignant melanoma: a clinicopathologic study of 192 cases with emphasis on the morphologic spectrum.

Metastatic melanoma represents one of the most common types of cutaneous metastases. In up to 5% of patients, metastatic melanoma can be the first manifestation of the disease. For the most part, the histologic diagnosis of metastatic melanoma poses little diagnostic difficulty; however, some metastases may adopt unusual or unfamiliar appearances mimicking other benign and malignant conditions. We present a study of 192 cases of cutaneous metastatic melanomas with special emphasis on their spectrum of morphologic features. The patients were 115 men and 77 women, 23-91 years of age (mean 57 years). Most tumors were located on the proximal legs, scalp, and arms and ranged from 0.8 to 3.0 cm. One hundred ten cases showed the classic morphologic appearance of melanoma (well-circumscribed epithelioid dermal/subcutaneous nodule), 82 cases showed unusual histologic appearances that mimicked other benign and malignant neoplasms. In 16 patients (8.3%), there was no evidence of primary melanoma and the cutaneous metastasis was the only manifestation of the disease. The histologic diagnosis of cutaneous metastatic melanoma can pose difficulties for diagnosis, especially in the face of an unknown primary neoplasm. Unusual features observed in this series included examples of cutaneous metastatic melanoma that closely simulated metastatic carcinoma, dermatofibroma, leiomyosarcoma, angiosarcoma, nevoid melanoma, halo nevus, blue nevi, and atypical fibroxanthoma. Several cases also showed rhabdoid, balloon cell, and alveolar features. Immunohistochemical stains plus careful clinical history helped to establish the correct diagnosis. Our series illustrates that the differential diagnosis of cutaneous metastatic melanoma can be broad and difficult. To the best of our knowledge, this is the largest series of cutaneous metastatic melanomas reported in the literature.

Immunohistochemical expression of S100A6 in cellular neurothekeoma: Clinicopathologic and immunohistochemical analysis of 31 cases

Neurothekeoma is a term introduced by Gallager and Helwig describing a superficial tumor of purported nerve sheath derivation, with cellular and myxoid types. Recently, it has been suggested that the cellular type does not have nerve sheath differentiation. This subtype represents an uncommon neoplasm and sometimes can be problematic to diagnose because it can be easily mistaken for melanoma. We studied the immunohistochemical features of 31 cases of cellular neurothekeomas to evaluate their immunoprofile. Immunohistochemical studies were performed in all 31 cases with formalin-fixed paraffin-embedded tissue sections with antibodies against S100 protein, S100A6, and melanoma antigen recognized by T-cells (MART-1). In addition, 8 cases were evaluated for HMB-45 antigen, keratin (with a pankeratin cocktail), epithelial membrane (EMA), and smooth muscle antigen (SMA). The lesions were from 8 men and 23 women aged 6-64 years (mean 35 years). Four tumors were located on the nose; 4 scalp; 4 finger; 3 thigh; 2 shoulder; 2 wrist; 2 hand; and 1 each on pelvis, cheek, toe, chest, eyebrow, forearm, penis, axilla, mouth, and leg. All tumors were positive for S100A6 (100%) and negative for cytokeratin, HMB-45 antigen, MART-1, and EMA (100%); 29 cases were negative for S100 protein (93.5%; the 2 positive cases had only scattered cells labeled), and only 2 cases were focally positive for SMA (7.5%). Therefore, the combination of strong immunoreactivity for S100A6, in nested dermal spindle cell proliferations, and lack of S100 protein or keratin, supports a diagnosis of cellular neurothekeoma.

Expression of immunohistochemical markers in primary and metastatic malignant melanoma: a comparative study in 70 patients using a tissue microarray technique.

Melanoma can show a broad spectrum of immunoreactivity and exhibit aberrant expression of antigens or changes in immunophenotype, particularly at metastatic sites. We studied 70 primary melanomas and their metastases with a broad panel of immunohistochemical markers using a tissue microarray technique to determine possible antigenic shift between the primary lesions and their metastases. Representative tissue cores were taken and processed from each case, and the tissue microarrays were stained by standard methods using antibodies to vimentin, bcl-2, CD117, carcinoembryonic antigen, epithelial membrane antigen, S-100 protein, HMB-45, cytokeratin AE1/AE3, Melan-A, TTF-1, CD99, and tyrosinase. Histologically, all the melanomas were of the classic epithelioid type. A slight increase in the expression of Melan-A was noted in metastatic lesions as opposed to the primary tumors (63% vs. 48.4%). Expression of other melanoma-associated markers, including S-100 protein and tyrosinase was only slightly decreased at metastatic sites as opposed to the primary tumor. Increased aberrant expression of epithelial-associated markers, including epithelial membrane antigen and cytokeratin AE1/AE3 was also noted in the metastases. bcl-2, CD117, and TTF-1 also showed a modest increase in antigenic expression at metastatic sites over the primary lesions. The results of this study demonstrated minimal antigenic shift between primary and metastatic melanoma for some of the more conventional melanocytic markers, it showed increased expression of aberrant markers and oncogene expression at metastatic sites.

Cutaneous CD30‐positive lymphoproliferative disorders with CD8 expression: a clinicopathologic study of 21 cases

Lymphomatoid papulosis (LyP) and cutaneous anaplastic large cell lymphoma (ALCL) belong to the spectrum of cutaneous CD30+ lymphoproliferative disorders, an indolent form of T‐cell lymphoproliferative disease. We reviewed 21 cases of CD30+ lymphoproliferative lesions expressing cytotoxic profile (CD8+). Seven cases of cutaneous ALCL, 2 cases of systemic ALCL involving the skin, and 12 cases of LyP. The cases of LyP were predominated by small lymphocytes exhibiting a prominent epidermotropic pattern consistent with either type B or type D LyP. Four cases showed co‐expression of CD56. The ALCL cases included myxoid features, pseudoepitheliomatous change, and an intravascular component. In all cases that were primary in the skin an indolent clinical course was seen while one patient with systemic myxoid ALCL is in remission following systemic multiagent chemotherapy. The paucity of other neutrophils and eosinophils and concomitant granulomatous inflammation were distinctive features in cases of type B and type D LyP. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful differentiating features from an aggressive cytotoxic CD8+ T cell lymphoma. In all cases that were primary in the skin an indolent clinical course was observed. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful in preventing a misdiagnosis of an aggressive cytotoxic CD8+ T cell lymphoma.