Expression and distribution of kallikrein-related peptidases 5, 7, 8 and 10 in normal apocrine gland of canine skin / Expresión y distribución de péptidos relacionados con la calicreína 5, 7, 8 y 10 en glándula apocrina normal de piel canina

SUMMARY: Apocrine glands are sweat glands that are located in the skin of the dog. Anal sac apocrine, circunanal apocrine, and mammary glands are considered modified apocrine structures, and there are about nine possible types of neoplasms and other tumors in the apocrine glands of the dog and cat, including cysts, adenoma, carcinoma, and adenocarcinoma. Thus, it is important to provide new markers to characterize these glands to improve the histopathological diagnosis. In this article, we describe the distribution of kallikrein- related peptidases 5, 7, 8, and 10 in the normal apocrine glands of the dog's skin. These proteases have been shown to play a fundamental role in the homeostasis of the human skin barrier but have been scarcely studied in canine skin.

Las glándulas apocrinas son glándulas sudoríparas que se encuentran en la piel del perro. Las glándulas apocrinas del saco anal, apocrinas circunanales y mamarias se consideran estructuras apocrinas modificadas, y existen alrededor de nueve tipos posibles de neoplasias y otros tumores en las glándulas apocrinas del perro y el gato, incluidos quistes, adenoma, carcinoma y adenocarcinoma. Por lo tanto, es importante proporcionar nuevos marcadores para caracterizar estas glándulas para mejorar el diagnóstico histopatológico. En este artículo, describimos la distribución de las peptidasas 5, 7, 8 y 10 relacionadas con la calicreína en las glándulas apocrinas normales de la piel del perro. Se ha demostrado que estas proteasas desempeñan un papel fundamental en la homeostasis de la barrera de la piel humana, pero apenas se han estudiado en la piel canina.

Apocrine Variant of Pleomorphic Lobular Carcinoma In Situ: Further Clinical, Histopathologic, Immunohistochemical, and Molecular Characterization of an Emerging Entity.

To date, the apocrine variant of lobular carcinoma in situ (AP-LCIS) has been cursorily described as a subtype of lobular carcinoma in situ (LCIS). We retrospectively reviewed 34 cases of AP-LCIS (including 23 associated with invasive lobular carcinoma) to fully characterize it. AP-LCIS typically presented with screen-detected calcifications in older women (mean age: 65 y) and was characterized by distended terminal duct lobular units with relatively large "pleomorphic" cells, central necrosis, and calcifications. AP-LCIS cells exhibited abundant eosinophilic occasionally granular cytoplasm, hyperchromatic nuclei, and prominent nucleoli. Synchronous classic and/or florid LCIS was identified in 24/34 (70%) AP-LCIS, and in 9/11 (82%) pure AP-LCIS. Most (68%) cases of AP-LCIS were estrogen receptor-positive (50% strongly), 35% were progesterone receptor-positive, 26% were human epidermal growth factor 2-positive, 18% demonstrated high-proliferation rate (Ki67: >15%), and 90% were androgen receptor-positive. Aurora kinase A, immunoreactive in 38% of AP-LCIS cases, was not significantly associated with recurrence, development of invasion, or nodal positivity (P>0.05). Compared with conventional (nonapocrine) pleomorphic lobular carcinoma in situ (P-LCIS), aurora kinase A was expressed in a significantly greater proportion of P-LCIS (100%). AP-LCIS and P-LCIS did not otherwise differ in clinicopathologic features. Next-generation sequencing utilizing the Oncomine Comprehensive Panel v2, performed on 27 AP-LCIS cases, showed no specific molecular findings. In a mean follow-up of 57 months, 2 (of 11, 18%) pure AP-LCIS cases recurred (2 both in situ and invasive) and none metastasized or proved fatal. AP-LCIS should be regarded as another high-grade LCIS similar to P-LCIS in many respects, and pending additional studies should be managed similarly.

Expression of growth hormone-releasing hormone receptors in apocrine adnexal tumours and apocrine glands of the skin.

Encouraged by our previous finding of growth hormone-releasing hormone receptor (GHRH-R) expression in metaplastic and neoplastic apocrine breast epithelium, we examined a small series of skin adnexal tumours with various degrees of apocrine (oxyphilic) differentiation, as well as normal axillary and anogenital apocrine sweat glands, for the expression of GHRH-R. Sections of formalin-fixed paraffin-embedded tissue blocks were immunostained for gross cystic disease fluid protein-15 (GCDFP-15) and androgen receptor (AR), to prove apocrine differentiation and correlate it with areas of GHRH-R expression. All but one of 19 tumours with apocrine epithelium and all five benign apocrine glands stained with both anti-GHRH-R antibodies used, each labelling a different domain of the receptor. Non-apocrine areas of the tumours and four eccrine tumours without oxyphilic features did not stain, but most sebaceous glands and some eccrine glands were labelled. Our data suggest that anti-GHRH-R antibodies highlight apocrine differentiation at extramammary sites also. Although GHRH-R seems to have a sensitivity comparable to classic apocrine markers such as AR and GCDFP-15, it seems to be inferior in specificity. The GHRH-R labelling of apocrine glands and neoplastic epithelium might also interfere with the emerging anti-GHRH targeted treatment of some malignancies acting on these receptors.

Cutaneous Apocrine Carcinoma With an In Situ Component and Histiocytoid and Signet-Ring Cells.

We present a case of cutaneous apocrine carcinoma arising in the axilla of a 71-year-old man. The tumor had a significant component of histiocytoid and signet-ring cells as well as in situ carcinoma within the apocrine glands. The cells expressed GATA3, gross cystic disease fluid protein 15, androgen receptor, and E-cadherin. Estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 were negative. Clinical correlation was required to rule out a metastasis from the breast or the gastrointestinal tract. Although most cutaneous apocrine carcinomas do not behave aggressively, our patient developed bone metastases and eventually died of his disease. It is debated whether histiocytoid and signet-ring cell cutaneous carcinomas should be classified as apocrine neoplasm. The presence of in situ carcinoma associated with this kind of tumor has been reported only once in the literature. This characteristic and the immunohistochemical profile are in favor of apocrine differentiation.

The expression of GHRH and its receptors in breast carcinomas with apocrine differentiation-further evidence of the presence of a GHRH pathway in these tumors.

Apocrine breast carcinomas were evaluated for the expression of components of the growth hormone-releasing hormone (GHRH) autocrine/paracrine pathway: GHRH and its receptors (GHRH-R), as mammary apocrine carcinomas and epithelium seemed to be uniformly positive for GHRH-R in a pilot study. The apocrine phenotype was determined on the basis of hematoxylin-eosin morphology and a congruent immunohistochemical profile (estrogen receptor negativity, androgen receptor and gross cystic disease fluid protein-15 positivity). Thirty-five formalin-fixed, paraffin-embedded apocrine breast cancers in tissue microarrays and 24 cases using whole-tissue sections were evaluated for GHRH-R and GHRH expression by immunohistochemistry using polyclonal antibodies raised against various domains of GHRH-R and one polyclonal antibody specific for GHRH. GHRH-R positivity was detected in the overwhelming majority (ranging from 90% to 100%) of apocrine breast carcinomas with all but one of the antibodies applied. The expression was usually diffuse with only isolated cases showing positivity in less than 50% of tumor cells. With the PA5-33583 antibody, GHRH-R positivity was seen only in 73% of the cases in at least 50% of the tumor cells. GHRH expression was also present in all but one case tested, with more than 50% of the cells expressing it in 30/34 cases. These results support a high rate of GHRH-R and GHRH expression in apocrine breast carcinomas. Whether these findings can be exploited for the targeted treatment of apocrine breast carcinomas with GHRH antagonists requires further study.

Apocrine mixed tumor of the eyelid: a case report.

BACKGROUND: Apocrine mixed tumor is usually found in parotid glands. Its cutaneous counterpart is rare and its occurrence in the eyelids is even rarer. CASE PRESENTATION: This study reports an apocrine mixed tumor of the upper left eyelid in a 68 year-old lady with a history of breast cancer. This mass appeared about 3 years ago, as a slowly growing small nodule, and was completely excised. On microscopic examination, an encapsulated mass with epithelial and mesenchymal features was seen. The epithelial component presented tubular, cystic and infundibular structures while the mesenchymal component was fibrous in some areas and myxoid in others. Plasmacytoid hyaline cells, lipomatous change and focal calcification were appreciated focally. Immunohistochemical studies showed stromal staining for CD10, S-100, α-SMA and p63. Luminal cell layer of the epithelial component was positive for EMA, CK-7 and GCDFP-15 markers. The capsule was unbreached and no satellite lesions were appreciated. No evidence of relapse was evident after 16 months of follow-up. CONCLUSIONS: The diagnosis of eyelid tumors of adnexal origin can be challenging because they are rare and display a wide range of morphological patterns, as the tumor cells might differentiate along any line of the folliculosebaceous-apocrine system. Immunohistochemistry helps improve the accuracy of assessment.

Cutaneous Adenomyoepithelioma: Report of a Case and Review of the Literature.

Adenomyoepithelioma (AME) is a biphasic neoplasm of epithelial and myoepithelial cells. It is most commonly found in the breast, although rare cases have been reported from the lung, salivary glands, and skin. There are 5 well-documented cases of cutaneous AME in the literature. We report a new case of cutaneous AME. Our case was commingled with apocrine hidrocystoma. This is the first report of cutaneous AME in a male patient and the first to describe SOX10 immunostaining in cutaneous AME. We review the literature on cutaneous AME and note the greater than chance colocalization with other adnexal tumors. We speculate that AME may represent localized overgrowth of myoepithelial cells within a pre-existent sweat gland tumor. Histopathologists should be aware of the potential of SOX10-positive myoepithelial neoplasms to mimic nodular melanocytic proliferations.

A Comparative Study of Immunohistochemical Myoepithelial Cell Markers in Cutaneous Benign Cystic Apocrine Lesions.

The use of immunohistochemical markers for myoepithelial cells (MEC) is a useful tool in the distinction of benign from malignant epithelial neoplasms. Although their use in breast tumors is well recognized, little is known concerning its application in comparable cutaneous lesions. Using benign cutaneous cystic apocrine lesions as a study model, the aim of this study was to compare 5 immunohistochemical markers [calponin, p63, smooth muscle actin (SMA), cytokeratin 14, and CD10] in their effectiveness to highlight MEC. Cases of apocrine hidrocystoma and cystadenoma (n = 44) were reviewed with a particular emphasis on proliferative features and apocrine change. The MEC staining pattern and the intensity and distribution scores in proliferative (n = 29) and nonproliferative (n = 15) lesions were assessed, and the differences between the 2 groups were statistically analyzed using Fisher exact test. Calponin and SMA stained MEC in the most consistent manner. Being a nuclear stain, p63 was easy to interpret but typically showed discontinuous staining. Cytokeratin 14 not only effectively highlighted MEC but also stained some luminal epithelial cells in an unpredictable manner. Because of prominent background dermal fibroblast staining, CD10 was often difficult to interpret. Only SMA and p63 showed a statistically significant difference in MEC staining intensity scores between the proliferative and nonproliferative groups. Our results show that immunohistological staining for MEC in benign cystic apocrine lesions of the skin is variable. The authors recommend that a panel of markers that includes calponin and p63 be used and highlight the need for awareness of specific caveats associated with individual markers.

Immunohistochemical and molecular profiling of histologically defined apocrine carcinomas of the breast.

Despite the marked improvement in the understanding of molecular mechanisms and classification of apocrine carcinoma, little is known about its specific molecular genetic alterations and potentially targetable biomarkers. In this study, we explored immunohistochemical and molecular genetic characteristics of 37 invasive apocrine carcinomas using immunohistochemistry (IHC), fluorescent in situ hybridization (FISH), multiplex ligation-dependent probe amplification (MLPA), and next-generation sequencing (NGS) assays. IHC revealed frequent E-cadherin expression (89%), moderate (16%) proliferation activity [Ki-67, phosphohistone H3], infrequent (~10%) expression of basal cell markers [CK5/6, CK14, p63, caveolin-1], loss of PTEN (83%), and overexpression of HER2 (32%), EGFR (41%), cyclin D1 (50%), and MUC-1 (88%). MLPA assay revealed gene copy gains of MYC, CCND1, ZNF703, CDH1, and TRAF4 in 50% or greater of the apocrine carcinomas, whereas gene copy losses frequently affected BRCA2 (75%), ADAM9 (54%), and BRCA1 (46%). HER2 gain, detected by MLPA in 38% of the cases, was in excellent concordance with HER2 results obtained by IHC/FISH (κ = 0.915, P < .001). TOP2A gain was observed in one case, while five cases (21%) exhibited TOP2A loss. Unsupervised hierarchical cluster analysis revealed two distinct clusters: HER2-positive and HER2-negative (P = .03 and .04, respectively). NGS assay revealed mutations of the TP53 (2 of 7, 29%), BRAF/KRAS (2 of 7, 29%), and PI3KCA/PTEN genes (7 of 7, 100%). We conclude that morphologically defined apocrine carcinomas exhibit complex molecular genetic alterations that are consistent with the "luminal-complex" phenotype. Some of the identified molecular targets are promising biomarkers; however, functional studies are needed to prove these observations.

Unusual apocrine carcinoma with neuroendocrine differentiation: a cutaneous neoplasm may be analogous to neuroendocrine carcinoma with apocrine differentiation of breast.

Cutaneous apocrine carcinoma (AC) is a rare adnexal neoplasm that histologically can mimic breast carcinoma metastatic to the skin or apocrine carcinoma arising in ectopic breast tissue. As extremely rare condition, neuroendocrine differentiation may be observed in AC although its etiology and pathogenesis is still unclear. We report here a case of unusual AC with neuroendocrine differentiation in right labium majus pudenda. A 43-year-old woman presented with a 6-month history of an asymptomatic pea-sized brownish nodule in right labium majus pudenda without enlargement of inguinal lymph nodes and bilateral breast nodules. The mass was totally resected. Microscopically, the tumor was solitary and located in the deep dermis without epidermal connection. Tumor cells were arranged in a micronodular or formed massive solid nests separated by densely fibroblastic stroma. Scattered glandular or rosette-like structures were identified within the tumor nodules. Immunohistochemically, the tumor cells were diffusely positive to CK7, CEA, GCDFP-15, synaptophysin, estrogen and progesterone receptors. Part of tumor cells expressed androgen receptor, but they were negative to CK20, CK5/6, p63 and S-100. Because of its rarity and histogenesis complexity, there exist diagnostic challenges for pathologists to differentiate cutaneous AC with neuroendocrine differentiation from other carcinomas with apocrine or neuroendocrine features. Our case demonstrates that the tumor shares some features with mammary carcinoma and might originate from mammary-like sweat gland in anogenital region. The results suggest that, for the first time, primary cutaneous AC with neuroendocrine differentiation may be analogous to the mammary neuroendocrine carcinoma with apocrine differentiation in histological feature and biological behavior. Virtual Slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/7732276716685708.

Immunohistochemical analysis of steroid hormone receptors in hidradenitis suppurativa.

BACKGROUND: Hidradenitis suppurativa (HS) is an inflammatory follicular skin disease. In women and men, the condition starts after puberty, has a peak in the third decade, and is rare after the menopause in women. This age distribution suggests a hormonal influence in the pathogenesis of the disease. We therefore hypothesized that apocrine glands in HS patients have a different expression of androgen receptor (AR) and estrogen receptor (ER) compared with healthy skin. METHODS: Axillary, inguinal, and perianal skin biopsies from female and male patients with HS were immunohistochemically stained for AR and ER activities. Expression of both receptors in apocrine glands of HS patients was compared with expression in apocrine glands in normal axillary or inguinal skin of a control group of women. RESULTS: Twenty-two patients with HS were included (16 women), with 10 women in the control group. In the HS group, apocrine glands were present in 11 out of 22 skin biopsies and in the control group in 4 out of 10 biopsies. Expression of ER in the apocrine gland was weak and observed in 2 out of 4 patients in the control group and in none of the HS patients. Expression of the AR was strong and observed in all apocrine glands in both groups. CONCLUSIONS: We could not demonstrate a significant difference in the expression of ER and AR in apocrine glands in skin biopsies of patients with HS, compared with healthy skin biopsies. The exact relation between sex hormones and occurrence of HS therefore remains unclear.

5α-Androst-16-en-3α-ol ß-D-glucuronide, precursor of 5α-androst-16-en-3α-ol in human sweat.

5α-Androst-16-en-3α-ol (α-androstenol) is an important contributor to human axilla sweat odor. It is assumed that α-andostenol is excreted from the apocrine glands via a H2 O-soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H2 O-soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α-androstenol, ß-androstenol sulfates, 5α-androsta-5,16-dien-3ß-ol (ß-androstadienol) sulfate, α-androstenol ß-glucuronide, α-androstenol α-glucuronide, ß-androstadienol ß-glucuronide, and α-androstenol ß-glucuronide furanose. The occurrence of α-androstenol ß-glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative-ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α-androstenol was observed after incubation of the sterile human sweat or α-androstenol ß-glucuronide with a commercial glucuronidase enzyme, the urine-isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have ß-glucuronidase activities. We demonstrated that if α- and ß-androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H2 O-soluble precursor of α-androstenol in apocrine secretion should be a ß-glucuronide.

Immunohistochemical sweat gland profiles.

BACKGROUND: Human sweat glands are heterogeneous in their structures and functions. Accordingly, eccrine, apocrine, and apoeccrine glands are distinguished. AIMS: Some immunohistochemical markers are expected to distinguish the sweat gland types in their secretory and excretory parts. METHODS: This study used two sets of antibodies. The first panel was composed of antibodies directed to well-defined sweat gland structures. The molecular targets included the low-molecular-weight cytokeratins CAM 5.2, the S100-B protein, the epithelial membrane antigen (EMA), the carcinoembryonic antigen (CEA), and the lectin Ulex europaeus agglutinin-1 (UEA-1). A second exploratory panel of antibodies targeted syndecan-1 (CD138), NKI-C3 (CD63), and CD68. They were used to disclose some undescribed antigen expressions in human sweat glands. RESULTS: The first set of antibodies confirmed previous findings. The immunoreactivities of the three sweat gland types were similar in the excretory ducts. By contrast, they were distinguished in the deeper coiled secretory portions of the glands. CONCLUSION: Clues supporting their distinction and probably their functional activity were obtained by immunohistochemistry using the S100-B protein, CEA and CD63 antibodies. The immunoreactivity to the S100-B protein, CEA and CD63 possibly help identifying apoeccrine sweat glands or a peculiar functional activity of eccrine sweat glands.

Microbiological and biochemical origins of human axillary odour.

The generation of malodour on various sites of the human body is caused by the microbial biotransformation of odourless natural secretions into volatile odorous molecules. On the skin surface, distinctive odours emanate, in particular, from the underarm (axilla), where a large and permanent population of microorganisms thrives on secretions from the eccrine, apocrine and sebaceous glands. Traditional culture-based microbiological studies inform us that this resident microbiota consists mainly of Gram-positive bacteria of the genera Staphylococcus, Micrococcus, Corynebacterium and Propionibacterium. Among the molecular classes that have been implicated in axillary malodour are short- and medium-chain volatile fatty acids, 16-androstene steroids and, most recently, thioalcohols. Most of the available evidence suggests that members of the Corynebacterium genus are the primary causal agents of axillary odour, with the key malodour substrates believed to originate from the apocrine gland. In this article, we examine, in detail, the microbiology and biochemistry of malodour formation on axillary skin, focussing on precursor-product relationships, odour-forming enzymes and metabolic pathways and causal organisms. As well as reviewing the literature, some relevant new data are presented and considered alongside that already available in the public domain to reach an informed view on the current state-of-the-art, as well as future perspectives.

Histochemical analyses of anti-microbial substances in canine perianal skin with special reference to glandular structures.

Circumanal glands are prominent features of the canine perianal skin, which are often located near to the sebaceous glands and apocrine glands. As the functional relevance of circumanal glands is yet unknown, we studied the localisation of sialic acids and anti-microbial substances (lysozyme, immunoglobulin A, lactoferrin, ß-defensin) in these glandular structures by lectin histochemistry and immunohistochemistry. The glands exhibited a number of sialic acids that were linked to α2-6Gal/GalNAc and α2-3Galß1-4GlcNAc. Additionally, lysozyme, lactoferrin and ß-defensin could be demonstrated in the three types of skin glands, whereas IgA was only detectable in the apocrine glands. The results of the study suggest the specific significance of the circumanal glands. Independent of a certain endocrine role, their products may mainly function as protective agents to preserve the integrity of the anal region, considering that sialic acids and anti-microbial substances are important in defence mechanisms.

"Onycholemmal carcinoma." An unusual case with apocrine and sebaceous differentiation. Are these tumors a microcystic nail bed carcinoma?

Subungual malignant epithelial tumors with tricholemmal keratinization have rarely been described as "malignant proliferating onycholemmal cyst" and "onycholemmal carcinoma (OC)." We report an additional case of a slow growing OC occurring on the middle finger of a 58-year-old man, which was unusual as it showed sebaceous-apocrine differentiation, in addition to a nail bed carcinoma with tricholemmal microcysts. We therefore consider the descriptive term of microcystic nail bed carcinoma more appropriate than OC. It is recognized that none of the rare cases of OC meet the classical additional criteria proposed by Headington for tricholemmal carcinoma, that is, lobular arrangement, peripheral palisading, thickened basement membrane, and glycogen-positive tumors cells. On the other hand, we suggest that the term follicular microcysts of the nail bed should be retained to describe the true nature of subungual epidermoid inclusions, which show usually a limited differentiation toward the follicular isthmus. Therefore, the previous cases of OC without sebaceous-apocrine differentiation could be best classified as a microcystic nail bed carcinoma arising from the follicular microcysts of the nail bed, with a limited differentiation toward the keratinization of the follicular isthmus.

Immunohistochemical study of calretinin in normal skin and cutaneous adnexal proliferations.

Calretinin is a calcium-binding protein member of the EF-hand family. The presence of calretinin has been demonstrated in certain stages of the cellular cycle in a wide variety of normal and neoplastic tissues. The main aims of our study were (1) to investigate what structures of the normal skin and cutaneous adnexal proliferations express immunoreactivity for calretinin and (2) to determine the value of immunohistochemical expression for calretinin as a marker for follicular, sebaceous, apocrine, and eccrine differentiation in cutaneous adnexal proliferations. We studied 139 biopsy specimens, including 10 cases of normal skin of different locations and 129 benign and malignant cutaneous adnexal proliferations. In normal skin, we found that calretinin is expressed in the innermost cell layer of the outer root sheath in anagen hair follicle, in both the duct and sebolemma of the sebaceous gland, in the secretory portion of eccrine glands, and in mast cells of the stroma. In cutaneous adnexal proliferations, we found strong immunoreactivity for calretinin in tricholemmal cysts, tricholemmomas/inverted follicular keratoses, tumors of follicular infundibulum, and in some basal cell carcinomas. Focal positivity was also seen in trichoadenomas, trichoblastomas/trichoepitheliomas, pilomatricomas, proliferating tricholemmal tumors, pilar sheath acanthomas, trichofolliculomas, follicular hybrid cysts, cutaneous mixed tumors, steatocystomas, sebaceous hyperplasias, and sebaceomas. These results demonstrate that immunohistochemical study for calretinin may be helpful to identify the innermost cell layer of the outer root sheath in anagen hair follicle and the cutaneous adnexal proliferations showing differentiation toward this structure. Calretinin immunoreactivity supports eccrine differentiation in some sweat gland neoplasms, and it is also useful in identifying neoplasms with ductal sebaceous differentiation.

Anal apocrine carcinoma: a case report and literature review.

Apocrine carcinoma (AC) is an extremely rare skin appendage tumor, which is located at lower dermal and subcutaneous tissue. We report a case of an anal AC arising from an apocrine adenoma in the anal region, which is only the second case reported in this region. A 71-year-old male presented to clinic with soreness in the anal region for 6 weeks. An excisional biopsy was performed. Histologically, the lesion was poorly circumscribed, infiltrative, and was composed of small to medium sized glands extending to the surgical margins. There were centrally dilated large glands with duct-like openings into the mucosal surface. The larger central glands contain periodic acid-Schiff-positive eosinophilic acellular secretions. At the periphery, there were smaller glands with significant cytologic atypia and numerous mitoses. A diagnosis of AC was made making it the second case report of this very rare malignancy in this region. Although ACs usually do not have a fatal outcome, there have been case reports of distant metastases and even death from this disease, making histologic distinction of this malignancy from a benign apocrine adenoma important. Wide local excision is typically the treatment of choice, although Mohs micrographic surgery has also been used with similar success.