Comparative expression of trophoblast cell-surface antigen 2 (TROP2) in the different molecular subtypes of invasive breast carcinoma: An immunohistochemical study of 94 therapy-naive primary breast tumors.

BACKGROUND: Sacituzumab govitecan, targeting trophoblast cell-surface antigen 2 (TROP2), is approved for the treatment of triple-negative and hormone receptor-positive/HER2-negative breast cancers. However, detailed studies comparing TROP2 protein expression in the different molecular subtypes of breast cancer are limited, and definitive evidence supporting the use of TROP2 as a biomarker for predicting response to this agent in patients with breast cancer is currently lacking. OBJECTIVE: To compare the expression of TROP2 in the different molecular subtypes of breast cancer. METHODS: Immunohistochemical staining for TROP2 was performed on 94 therapy-naive primary invasive breast carcinomas, including 25 luminal A-like, 25 luminal B-like, 19 HER2-like, and 25 triple-negative tumors. RESULTS: Intermediate to high levels of TROP2 expression were observed in the majority of carcinomas of each molecular subtype, with a wide range of expression in each subtype. Occasional tumors with low or absent TROP2 expression were encountered, including two metaplastic carcinomas which were completely negative for TROP2. CONCLUSIONS: Our observations support the continued investigation of the efficacy of sacituzumab govitecan in all molecular subtypes of breast carcinoma. Furthermore, the observed wide range of expression of TROP2 suggests that TROP2 may have potential utility as a biomarker for predicting responsiveness to sacituzumab govitecan. If this proves to be the case, then immunohistochemical staining for TROP2 would be critical for identifying those patients whose tumors are completely negative for TROP2, since these patients may be least likely or unlikely to respond to this agent, and alternative therapies may be more appropriate in such instances.

Low-Grade Appendiceal Mucinous Neoplasms: A Single Institution Experience of 64 Cases With Clinical Follow-up and Correlation With the Current (Eighth Edition) AJCC Staging.

Background. In this single-institution study, we applied the current (eighth edition) American Joint Committee on Cancer pathologic staging criteria to 64 low-grade mucinous neoplasms of the appendix (LAMNs), examined their histopathologic features, and studied the patients' clinical outcomes. Design. Sixty-four LAMNs, with a median follow-up of 52 months, were reviewed. Results. The distribution of pathologic stages was pTis (n = 39), pT3 (n = 1), pT4a (n = 5), pT4aM1a (n = 8), and pT4aM1b (n = 11). Recurrence was observed in only 2 patients (both with pT4aM1b disease), one of whom died of disease. All remaining patients were disease-free after a median clinical follow-up of 60 months. Conclusions. Our study confirms that pTis LAMNs have an excellent prognosis and suggests that pT4a and pT4aM1a LAMNs may also have a low risk of developing progressive disease.

Comparison of metastatic neuroendocrine neoplasms to the breast and primary invasive mammary carcinomas with neuroendocrine differentiation.

Metastatic neuroendocrine neoplasms to the breast may show considerable morphologic overlap with primary mammary carcinomas, particularly those showing evidence of neuroendocrine differentiation, and may be misdiagnosed as such. Accurate distinction between these two entities is crucial for determination of appropriate clinical management. The histologic and immunohistochemical features of metastatic neuroendocrine neoplasms to the breast were studied and compared with the features of primary invasive mammary carcinomas with neuroendocrine differentiation, which served as controls. Of the metastatic neuroendocrine neoplasms, 15 were well-differentiated neuroendocrine tumors with carcinoid tumor-type morphology and 7 were poorly differentiated/high-grade neuroendocrine carcinomas with small-cell or large-cell neuroendocrine carcinoma morphology. The majority of the metastatic neoplasms originated in the lung and gastrointestinal tract. There were histologic similarities between metastatic neuroendocrine neoplasms and invasive mammary carcinomas with neuroendocrine differentiation, both of which exhibited neuroendocrine histologic features (nested and trabecular architecture, minimal tubular differentiation, and characteristic nuclear features). Only one case of the invasive mammary carcinomas with neuroendocrine differentiation was modified Bloom-Richardson grade 1 (largely due to minimal tubular differentiation on most such tumors), and the invasive mammary carcinomas with neuroendocrine differentiation were often associated with in situ carcinoma. Immunohistochemistry was helpful in distinguishing metastatic neuroendocrine neoplasms from invasive mammary carcinomas with neuroendocrine differentiation. Whereas the majority of invasive mammary carcinomas with neuroendocrine differentiation were positive for estrogen receptor and GATA3, metastatic neuroendocrine neoplasms were typically negative for estrogen receptor and GATA3, and metastatic well-differentiated neuroendocrine tumors often showed immunoreactivity for site-specific markers. Although the histologic and immunohistochemical features of a breast tumor may raise the suspicion of a metastatic neuroendocrine neoplasm, the pathologic findings should be interpreted in the context of the clinical history and imaging findings in order to establish an accurate diagnosis.

GATA3 Expression in Normal Skin and in Benign and Malignant Epidermal and Cutaneous Adnexal Neoplasms.

Initial investigations reported GATA3 to be a sensitive and relatively specific marker for mammary and urothelial carcinomas. Recently, GATA3 expression has been described in several other epithelial tumors. However, there has been only limited investigation of GATA3 expression in cutaneous epithelial tumors. The objective of this study was to examine the immunohistochemical expression of GATA3 in a wide variety of cutaneous epithelial neoplasms. GATA3 expression was evaluated in 99 benign and 63 malignant cutaneous epithelial tumors. GATA3 was consistently and usually strongly expressed in clear cell acanthoma, trichofolliculoma, trichoepithelioma, trichilemmoma, sebaceous adenoma, sebaceoma, apocrine hidrocystoma, apocrine tubular papillary adenoma, hidradenoma papilliferum, and syringocystadenoma papilliferum. Hidradenomas exhibited variable positive staining. Most poromas, syringomas, chondroid syringomas, cylindromas, and spiradenomas were negative or only focally and weakly positive. Focal staining was present in all pilomatrixomas. Thirteen of 14 basal cell carcinomas, 21 of 24 squamous carcinomas, and all 6 sebaceous carcinomas exhibited positive staining. The 1 apocrine carcinoma, both mucinous carcinomas, and 2 of 3 microcystic adnexal carcinomas also exhibited positive staining, whereas the 1 eccrine porocarcinoma and the 1 adenoid cystic carcinoma were negative. One of 11 Merkel cell carcinomas exhibited focal weak staining. Our findings demonstrate that GATA3 is expressed in a wide variety of benign and malignant cutaneous epithelial neoplasms. In addition to carcinomas of breast and urothelial origin and other more recently described GATA3-positive tumors, the differential diagnosis of a metastatic tumor of unknown primary origin that expresses GATA3 should also include a carcinoma of cutaneous epithelial origin.

Comparison of PAX6 and PAX8 as immunohistochemical markers for pancreatic neuroendocrine tumors.

To compare the utility of PAX6 and PAX8 as immunohistochemical markers for neuroendocrine tumors (NETs) of pancreatic origin, we performed PAX6 and PAX8 immunostains on 178 NETs, including 110 primary NETs (26 pancreatic, 10 gastric, 12 duodenal, 22 jejuno-ileal, 10 rectal, 30 pulmonary) and 68 NETs metastatic to the liver (24 pancreatic, 1 duodenal, 37 jejuno-ileal, 1 rectal, 5 pulmonary). Among primary NETs, PAX6 and PAX8 were positive in 65 % (17/26) and 73 % (19/26) of pancreatic, 0 % (0/10) and 10 % (1/10) of gastric, 92 % (11/12) and 92 % (11/12) of duodenal, 0 % (0/22) and 0 % (0/22) of jejuno-ileal, 90 % (9/10) and 80 % (8/10) of rectal, and 0 % (0/30) and 23 % (7/30) of pulmonary NETs, respectively. PAX6 and PAX8 positivity was seen in 46 % (11/24) and 50 % (12/24) of metastatic pancreatic NETs to the liver, respectively. None of the nonpancreatic NETs metastatic to the liver were immunoreactive for either PAX6 or PAX8. PAX6 showed a slightly but statistically significant higher specificity for pancreatic NETs than did PAX8 (P = 0.039), while the sensitivities were similar (P = 0.51). PAX6 had the additional advantages over PAX8 of not exhibiting nonspecific cytoplasmic staining of tumor cells and only infrequently staining background lymphocytes. Since rectal NETs rarely present with metastatic disease, positive staining of a metastatic NET of unknown primary origin for PAX6 and/or PAX8 favors a pancreatic or duodenal origin. This information may be helpful in directing further diagnostic studies to identify the primary site of the metastatic tumor.

The immunohistochemical expression of islet 1 and PAX8 by rectal neuroendocrine tumors should be taken into account in the differential diagnosis of metastatic neuroendocrine tumors of unknown primary origin.

Rectal neuroendocrine tumors (NETs) can be classified by histologic pattern and secretory products. Recently, rectal NETs have been noted to exhibit immunohistochemical (IHC) positivity for Islet 1 and PAX8, which are generally considered markers for NETs of pancreatic origin. In this study, we sought to characterize the IHC staining profile of rectal NETs and determine whether there was any correlation between the histologic pattern of rectal NETs and their IHC profile. Fifty-six primary rectal NETs were histologically reviewed and stained with antibodies against Islet 1, PAX8, CDX2, chromogranin A, and synaptophysin. In a subset of 31 cases, immunoreactivity for serotonin, pancreatic polypeptide (PP), and prostatic acid phosphatase (PAP) was also studied. By morphology, the tumors studied included 55 % trabecular, 27 % solid nested, 4 % acinar, and 14 % mixed patterns. Islet 1 was positive in 89 % and PAX8 in 79 % of cases. CDX2 was negative in all 56 cases. Cytoplasmic staining was observed for chromogranin A in 30 % of cases and for synaptophysin in all 56 cases. Cytoplasmic staining for serotonin, PP, and PAP was present in 16, 61, and 97 % of cases, respectively. There was no correlation between histologic pattern and IHC staining pattern with any of the antibodies studied. We have demonstrated that Islet 1 and PAX8 are not entirely specific for NETs of pancreatic origin, as they are expressed in a majority of rectal NETs. Since rectal NETs may show an IHC staining profile which mirrors that of pancreatic NETs (Islet 1 and PAX8-positive, CDX2-negative), a metastatic rectal NET should be considered in the differential diagnosis and ruled out clinically in the work-up of a metastatic NET of unknown primary origin which exhibits this staining profile.

Value of Islet 1 and PAX8 in identifying metastatic neuroendocrine tumors of pancreatic origin.

Neuroendocrine tumors can present as liver metastases before discovery of the primary tumor. Islet 1 and PAX8 have recently been proposed as markers for neuroendocrine tumors of pancreatic origin. In this study, we compared the utility of Islet 1 and PAX8 in distinguishing pancreatic neuroendocrine tumors from neuroendocrine tumors of other sites and determined the usefulness of an immunohistochemical panel, including TTF1, CDX2, Islet 1 and/or PAX8, in identifying metastatic pancreatic neuroendocrine tumors. A total of 110 primary neuroendocrine tumors (33 pancreatic, 31 pulmonary, 23 ileal, 14 rectal, and 9 gastric) and 73 metastatic neuroendocrine tumors (28 pancreatic, 5 pulmonary, 37 ileal, 1 rectal, 1 colonic, and 1 duodenal) were studied. Islet 1 and PAX8 were positive in 27/33 (82%) and 29/33 (88%), respectively, of primary pancreatic neuroendocrine tumors, and in 19/28 (68%) and 15/28 (54%), respectively, of metastatic pancreatic neuroendocrine tumors. No cases of primary (0/23) or metastatic (0/37) ileal neuroendocrine tumors were positive with either Islet 1 or PAX8. There was Islet 1 positivity in 2/31 (6%) primary pulmonary, 12/14 (86%) primary rectal, and 1/1 metastatic rectal neuroendocrine tumors, and PAX8 positivity in 7/31 (23%) primary pulmonary, 11/14 (79%) primary rectal, and 2/9 (22%) primary gastric neuroendocrine tumors. ROC curve analysis incorporating sensitivity and specificity data of immunohistochemical panels for metastatic pancreatic neuroendocrine tumors showed that a four-stain panel, including Islet 1, PAX8, TTF1, and CDX2 significantly outperformed a three-stain panel composed of PAX8, TTF1, and CDX2 (P=0.019), and also showed a trend for better performance compared with a three-stain panel composed of Islet 1, TTF1, and CDX2 (P=0.072). Both Islet 1 and PAX8 are reliable immunohistochemical markers for pancreatic neuroendocrine tumors and would be useful adjuncts to other markers (TTF1, CDX2) currently used to work up a metastatic neuroendocrine tumor of unknown primary.

Pigmented adrenocortical carcinoma: case report and review.

Darkly pigmented adrenocortical neoplasms are rare tumors that are often referred to as "black adenomas," indicative of both their pigmented nature and their invariably benign clinical behavior in previously reported cases. We herein describe an exceptional case of a malignant pigmented adrenocortical neoplasm, with late recurrence and metastasis. At age 53, this female patient was diagnosed with Cushing's syndrome and underwent a laparoscopic right adrenalectomy, revealing a 3 cm well-circumscribed, darkly pigmented adrenocortical tumor. The tumor exhibited several atypical histologic features and was diagnosed as an atypical pigmented adrenal cortical neoplasm of uncertain malignant potential. Eight years later, the patient developed clinical and biochemical evidence of recurrent Cushing's syndrome, and imaging studies revealed the presence of several masses in the right retroperitoneum. At subsequent exploratory laparotomy, three separate tumor nodules exhibiting varying degrees of pigmentation and ranging from 2.2 to 3.3 cm maximum dimension were excised. Histologically, the tumor nodules were consistent with local recurrence/metastasis of the patient's previously excised pigmented adrenocortical neoplasm.

Cartilaginous metaplasia in calcified diabetic peripheral vascular disease: morphologic evidence of enchondral ossification.

The mechanism of arterial calcification is not clear. We examined histological sections of major arteries from lower extremities of two patients with longstanding type II (or non-insulin-dependent) diabetes mellitus, and found morphological evidence of cartilaginous metaplasia and ectopic ossification with associated severe medial arterial calcification and atherosclerosis. Hematoxylin and eosin, alcian blue, and toluidine blue stains were applied for the demonstration of cartilage cells and their specific matrix proteins, and immunohistochemical studies for type II collagen. To our knowledge, cartilaginous metaplasia has not previously been described in medium-sized human muscular arteries. This observation supports the hypothesis that active enchondral ossification may be a pathway leading to arterial calcification in diabetic obstructive peripheral vascular disease.