The role of DOG1 immunohistochemistry in dermatopathology

Transcriptional repressor GATA binding 1 (TRPS1) immunoexpression in normal skin tissues and various cutaneous tumors

BACKGROUND

Transcriptional repressor GATA binding 1 (TRPS1) is a transcription factor recently shown to play a role in the development of breast and liver cancer. Here, we evaluate TRPS1 immunoexpression in normal skin tissues and various cutaneous tumors.

METHODS

TRPS1 immunohistochemistry was performed in 109 cases of primary cutaneous tumors and 19 cases of metastatic carcinomas. TRPS1 expression was also evaluated in the normal skin tissues.

RESULTS

The normal epidermis was TRPS1-. In contrast, the eccrine apparatus, epithelial compartment of the hair follicles, hair papilla, sebaceous glands, and anogenital mammary-like glands were TRPS1+. In primary cutaneous tumors, TRPS1 positivity varied in poroma (2/3), nodular hidradenoma (4/5), spiradenoma (4/4), cutaneous mixed tumor (5/5), trichilemmal cyst (7/8), proliferating trichilemmal tumor (1/3), pilomatricoma (9/9), sebaceoma (2/5), extramammary Paget disease (13/13), sebaceous carcinoma (2/2), actinic keratosis (3/10), Bowen disease (7/12), and squamous cell carcinoma (1/5) cases. All cases of seborrheic keratosis, basal cell carcinoma, Merkel cell carcinoma, and malignant melanoma were TRPS1-. All metastatic breast carcinoma cases (8/8) were highly positive for TRPS1, while all but one of the other metastatic tumor cases were TRPS1-.

CONCLUSIONS

TRPS1 immunoexpression was observed in several skin appendages and cutaneous tumors.

DOG1 expression in neuroendocrine neoplasms: Potential applications and diagnostic pitfalls

Neuroendocrine neoplasms represent a heterogeneous group of rare tumors, more frequently arising from gastroenteropancreatic tract and lungs. At the time of diagnosis, 20% of cases are metastatic, and 10% of cases are considered as cancer of unknown primary origin. Several immunohistochemical markers are routinely used to confirm the neuroendocrine differentiation, first among all Synaptophysin and Chromogranin-A; on the other hand, different immunohistochemical markers are used to establish primary anatomical site, as TTF1, CDX2, Islet-1 and Calcitonin, but no marker is available in order to distinguish among different sites of the digestive tract. DOG1 (discovered on GIST-1) is a gene normally expressed in interstitial cells of Cajal and, in routine practice, DOG1 immunostaining is used in diagnosis of GIST (gastrointestinal stromal tumor). DOG1 expression has been described in several neoplasms other than GIST, both in mesenchymal and epithelial neoplasms. In the present study, DOG1 immunostaining has been performed in a large cohort of neuroendocrine neoplasms, including neuroendocrine tumors and neuroendocrine carcinomas, in order to evaluate frequency, intensity and pattern of expression in different anatomical site and in different tumor grade. DOG1 expression was detected in a large percentage of neuroendocrine tumors, with statistically significant association between DOG1 expression and gastrointestinal tract neuroendocrine tumors. As a consequence, DOG1 could be included in marker panel for the identification of primary site in neuroendocrine metastases of unknown primary origin; moreover, these results recommend careful evaluation of DOG1 expression in gastrointestinal neoplasms, in particular in differential diagnosis between epithelioid GIST and neuroendocrine tumors.

DOG-1 as a Myoepithelial Marker in Discriminating Invasive Breast Carcinomas From Non-Invasive Breast Lesions

Introduction The most common cancer in women is, by far, breast cancer. The incidence and mortality of breast cancer must be reduced by a multidisciplinary strategy that includes education campaigns, preventive measures, screening programmes for early diagnosis, and the availability of treatment facilities. The use of immunohistochemical (IHC) stains with relative specificity for myoepithelial markers has become a mainstay of standard diagnostic breast pathology because the presence and distribution of myoepithelial cells might differ greatly amongst the distinct breast proliferation. Although it has also been reported that DOG1 is expressed in other mesenchymal tumours, DOG1 has been demonstrated to be sensitive and specific for the detection of gastrointestinal stromal tumors (GISTs). Both myoepithelial cells (MECs) and luminal epithelial cells have occasionally displayed DOG1 immunoreactivity in the breast. Materials and methods This prospective cross-sectional study was done in the Department of Pathology at Osmania General Hospital, Hyderabad on 60 cases from June 2017 to June 2019. Female patients with different breast lesions including benign proliferating lesions, ductal carcinoma in-situ (DCIS), and invasive carcinoma breast cases were included in the study. Inflammatory lesions, mesenchymal, and metastatic tumors were excluded. IHC expression of DOG1 as a myoepithelial marker to discriminate invasive from non-invasive breast lesions was evaluated and correlated with clinicopathological features. Results The mean age of the study population was 33.67 ± 8.48 in the benign group and 54.43 ± 12.84 in the malignant group. Fifty percent (15) of the patients with benign lesions belonged to the age group 20-30 years, whereas 26.7% (8) of the patients with malignant lesions belonged to the age group 61-70 years. DOG-1 expression was strongly positive in fibroadenoma, ductal hyperplasia, fibrocystic disease, whereas strongly negative in malignant disease of the breast (p < 0.0001). P63 expression was strongly positive in benign breast diseases and strongly negative in malignant diseases (p < 0.0001). Conclusion DOG1 seems to be similar to p63 as a myoepithelial cell marker both in normal breast tissue and in benign lesions. DOG1 is strongly positive in benign breast diseases and strongly negative in malignant breast diseases. Hence, it can be considered as a useful myoepithelial marker in differentiating invasive breast carcinoma and non-invasive breast lesions.

Sox10 and DOG1 Expression in Primary Adnexal Tumors of the Skin

Primary skin adnexal tumors can be challenging to classify and must be discerned from cutaneous adenocarcinoma metastases from various sites. We evaluated expression of Sox10 and DOG1 in normal cutaneous adnexa and in 194 primary skin adnexal tumors, and compared their performance in discriminating primary skin adnexal tumors from cutaneous metastatic adenocarcinomas with that of p40 and p63. In normal skin adnexa, we noted Sox10 expression in both the secretory and myoepithelial cells in eccrine glands, but only in myoepithelial cells in apocrine glands. DOG1 demonstrated canalicular expression in eccrine glands, and weak expression in myoepithelial cells of apocrine glands, germinative cells of sebaceous glands, and outer root sheath of follicular infundibulum. Sox10 was expressed in 100% of cylindromas and spiradenomas, and in variable frequency in other benign and malignant tumors of sweat glands. DOG1 was positive in most cylindromas (87.5%), in only 10.5% of spiradenomas, and was variably expressed in other benign and malignant tumors of sweat glands. All syringomas (n = 20) were negative for Sox10 and DOG1. One out of the 33 follicular neoplasms was positive for Sox10 and DOG1 (3%). All sebaceous neoplasms were negative for Sox10, and 28.1% of them were positive for DOG1. Sox10 was specific (91.9%) but not sensitive (28.4%) for primary skin origin, and was far less accurate (38.5%) than p63 or p40 (95.5% accuracy). Combining Sox10 with p63 or p40 showed only very minimal gain in accuracy (96%). DOG1 expression in tumors showed low sensitivity and specificity for skin adnexal origin.

Regulation of epithelial ion transport in exocrine glands by store-operated Ca2+ entry

Store-operated Ca²⁺ entry (SOCE) is a conserved mechanism of Ca²⁺ influx that regulates Ca²⁺ signaling in many cell types. SOCE is activated by depletion of endoplasmic reticulum (ER) Ca²⁺ stores in response to physiological agonist stimulation. After it was first postulated by J.W. Putney Jr. in 1986, SOCE has been described in a large number of non-excitable cell types including secretory cells of different exocrine glands. Here we discuss the mechanisms by which SOCE controls salt and fluid secretion in exocrine glands, with a special focus on eccrine sweat glands. In sweat glands, SOCE plays an important, non-redundant role in regulating the function of Ca²⁺-activated Cl^- channels (CaCC), Cl^- secretion and sweat production. In the absence of key regulators of SOCE such as the CRAC channel pore subunit ORAI1 and its activator STIM1, the Ca²⁺-activated chloride channel TMEM16A is inactive and fails to secrete Cl^-, resulting in anhidrosis in mice and human patients.