Value of Immunohistochemistry to Differentiate Digital Papillary Adenocarcinoma From Acral Hidradenoma With Papillary Structures.

ABSTRACT: Digital papillary adenocarcinoma is a malignant adnexal tumor with a predilection for acral sites. Hidradenoma is a benign solid and cystic sweat gland neoplasm with focal ductal and glandular differentiation and good outcomes. Hidradenomas can occur at acral sites and show papillary structures; for this reason, they are included in the differential diagnosis of digital papillary adenocarcinoma, and immunohistochemistry is a valuable tool in this scenario. We described a case of a 43-year-old man with an epithelial tumor showing papillary structures in the intermediate phalanx of the fourth finger. There was diffuse positivity for p63 and negativity for S100 protein, suggesting that this tumor was an acral hidradenoma with papillary structures.

Association of HPV42 with digital papillary adenocarcinoma and the use of in situ hybridization for its distinction from acral hidradenoma and diagnosis at non-acral sites.

Digital papillary adenocarcinoma (DPAC) is a rare tumor of sweat gland origin that preferentially affects the digits and has the potential to metastasize. Its tumor diagnosis can be difficult. Well-differentiated variants of DPAC can be confused with a benign sweat gland tumor, in particular nodular hidradenoma. With the recent detection of HPV42 DNA in DPAC by next-generation sequence analysis, we reasoned that this association could be used for diagnostic purposes. To this end, we performed in situ hybridization for HPV42 on 10 tumors diagnosed as DPAC as well as 30 sweat gland tumors of various histology types, including 8 acral hidradenomas. All DPAC were positive for HPV42. Positive hybridization signals for HPV42 were seen in both primary and metastatic DPACs. All other tumors and normal tissues were negative. This study confirms the association of HPV42 with the tumor cells of DPAC through in situ hybridization. The positive test result in all lesions of DPAC and lack of detection of HPV42 in any of the acral hidradenomas or other sweat gland tumors examined in this series is encouraging for the potential diagnostic utility of the assay. As documented by two scrotal tumors of DPAC, the in situ hybridization test for HPV42 can also help support the rare occurrence of this tumor at a non-acral site.

PIGMENTED NODULAR CYSTIC HIDRADENOMA OF THE ANKLE.

Solid-cystic hidradenoma is a benign cutaneous tumor that is most commonly found in the head, neck, trunk, and upper extremity regions of patients in the middle to older aged groups. Presentation on lower extremities and in particular on the foot is uncommon. Nodular hidradenomas represent a dermatological pitfall, being difficult to differentiate from basal cell carcinoma and melanoma. We report on a 53-year-old male patient with a pigmented nodular hidradenoma on his ankle that was surgically removed. We discuss histopathology and differential diagnosis of this eccrine tumor of skin. This is the second reported case in the English literature.

A rare case of Hidradenoma of the lower lip.

Hidradenoma are rare benign tumors with eccrine or apocrine differentiation that most often presents as a small, firm, solitary dermal nodule. At times, hidradenoma shows striking cytologic and histologic similarity to other neoplasms, including its malignant counterpart, hidradenocarcinoma. We present the first reported case of benign hidradenoma of the lower lip. The case illustrates important diagnostic features of hidradenoma and discusses the current understanding of its malignant potential and the appropriate management of such lesions.

Primary Biphasic Hepatic Sarcoma in DICER1 Syndrome.

DICER1 tumor predisposition syndrome is a rare genetic disorder that predisposes individuals to multiple benign and malignant neoplasms. The phenotype is vast and includes pleuropulmonary blastoma (PPB), thyroid nodules, cystic nephroma, Wilms tumor, ovarian Sertoli-Leydig cell tumor, and medulloepithelioma, among others. Herein, we describe a patient with a DICER1 germline pathogenic variant presenting with two neoplasms that are not commonly encountered in the context of DICER1 syndrome. The first tumor is a multiloculated cystic hepatic lesion with a biphasic pattern, composed of cysts lined by bland biliary type (CK19-positive) epithelium surrounded by a condensation of sarcomatous spindled cell proliferation in a myxoid stroma. This neoplasm resembled PPB or cystic nephroma with malignant transformation. The second tumor is a chest nodule consistent with low-grade hidradenocarcinoma. Although it is difficult to speculate with just a single case, these unusual neoplasms occurring in particular at a young age raises the possibility that they can be inherent to, and thus, be part of the DICER1 tumor predisposition syndrome phenotype.

A rare case of malignant eccrine spiradenoma mimicking carcinosarcoma.

Malignant eccrine spiradenoma is an extremely rare neoplasm of adnexal origin. It almost always originates from a preexisting long standing eccrine spiradenoma. We present a case of malignant eccrine spiradenoma arising from benign counterpart and having both carcinomatous and sarcomatous differentiation. Here we present a case of a 46 years old lady who presented with a long standing small nodule on her left leg of 7 years' duration with suddenly increase in size. Grossly the mass was partly solid and partly cystic measuring 11.5 cm in maximum dimension with cystic area forming the deeper plane. On microscopy, the superficial dermis showed well demarcated lobules of benign eccrine spiradenoma. Deeper dermis showed tumor cells with features of malignant transformation having both carcinomatous and sarcomatous component. After wide local excision patient is now doing well. The diagnosis of malignant eccrine spiradenoma requires a thorough histopathological examination of the lesion and requires finding a focus of benign spiradenoma within or adjacent to malignant tumour. Wide local excision and close follow-up for early detection of recurrence and metastasis is the mostly recommended management modality.

Rapidly Enlarging Hidradenoma of the Eyelid.

Hidradenoma is a rare benign neoplasm, with few cases reported to involve the eyelid. When affecting the eyelid, hidradenomas may mimic other benign or malignant lesions. Rarely, a benign hidradenoma may transform into a malignant hidradenoma and metastasize. The authors present a case of a benign hidradenoma arising from the eyelid, presenting with rapid growth, ulceration, and bleeding, suggestive of a malignant lesion.

Perineal Clear Cell Hidradenoma: A GATA3-positive Neoplasm With Potential for Misdiagnosis.

We report a case of clear cell hidradenoma of the perineum that was initially misinterpreted as a papillary urothelial carcinoma, either metastatic or of Bartholin gland origin, on initial excisional biopsy. The misinterpretation may have been due to the pseudopapillary architecture and GATA3-positivity of the biopsy tissue. Clear cell hidradenomas often show a range of histologic growth patterns and cellular differentiation and are one of many tumors that react immunohistochemically with GATA3. Although rare, these tumors can occur in the genital region and can mimic malignant tumors such as metastatic renal cell carcinoma and carcinomas of the genitourinary tract. This report details the morphologic and immunohistochemical pitfalls that make accurate diagnosis of clear cell hidradenoma in this unusual location challenging.

Clear Cell Hidradenoma of the Breast Diagnosed on a Core Needle Biopsy: A case report and review of the literature.

Clear cell hidradenoma (CCH) is a tumour originating from the eccrine sweat glands. It usually presents in the limbs, axilla or trunk. CCH of the breast is rare and can present as a cystic lesion in the breast that can be easily misdiagnosed as malignancy. We report a 36-year-old female patient who presented at the Sultan Qaboos University Hospital Breast Clinic, Muscat, Oman, in 2018 with a lump in her left breast. Ultrasound examination reported a complex cystic lesion with a solid, vascular component. An ultrasound-guided core needle biopsy was suggestive of clear cell hidradenoma. Surgical excision was performed and histopathology confirmed the diagnosis of CCH of the breast. This is the first ever case of a diagnosis of CCH made using core needle biopsy. CCH can be challenging to diagnose; therefore, awareness of its histopathological and ultrasonographic features are essential to avoid misdiagnosis and over treatment.

Clear cell papillary neoplasm of the breast with MAML2 gene rearrangement: Clear cell hidradenoma or low-grade mucoepidermoid carcinoma?

Clear cell hidradenoma (CCH) is an uncommon adnexal tumor usually arising from eccrine glands and commonly seen on the face and the upper extremities. CCH occurring in the breast is extremely rare. Herein we report a case of MAML2-rearranged CCH of breast with a papillary architecture closely mimicking intraductal papilloma, adenomyoepithelioma and low-grade mucoepidermoid carcinoma, thus representing a source of diagnostic confusion. An overview of salient histologic features and immunophenotypes to distinguish CCH and low-grade mucoepidermoid carcinoma is also integrated into the report.

Tubulopapillary hidradenoma-like tumor of the mandible: Two case reports of an underrecognized entity.

Tubulopapillary hidradenoma-like tumor of the mandible is extremely rare, with only 3 cases published in the English-language literature. The clinicopathological characteristics and histogenesis of this tumor are unclear. Few pathologists and perhaps fewer clinicians are familiar with this entity, and it is likely underrecognized and under-reported. Herein, we present two additional cases, both misdiagnosed as malignancies preoperatively and postoperatively by different unwary pathologists. Awareness and knowledge of this enigmatic entity and its clinical and radiographic features, together with careful morphological assessment should enable the correct diagnosis and prevent unnecessary treatment.

Primary Cutaneous Adenomyoepithelioma Ex Spiradenoma With Malignant Histologic Features, Epithelial-Myoepithelial Carcinoma Type: A First Case Report With Molecular Studies.

Adenomyoepithelioma is an extremely rare primary cutaneous neoplasm. Although there is ample evidence on the existence of malignant adenomyoepithelioma in the breast, a malignant counterpart in the skin has not been documented. We report a primary cutaneous adenomyoepithelioma (pcAME) with malignant features arising from a spiradenoma in a 39-year-old female patient. The tumor was solid-cystic in appearance and entirely located in the subcutaneous tissue. Histologically, the tumor displayed foci of adenomatous changes and adenomyoepitheliomatous hyperplasia adjacent to a minute spiradenoma. Gradual increase of architectural complexity, cytologic atypia, mitotic activity, and infiltrative growth were observed in a significant portion of the neoplasm, indicative of transformation to adenomyoepithelioma and subsequently low- to high-grade salivary-type epithelial-myoepithelial carcinoma (EMCA). The intimate dual populations of ductal and myoepithelial cells were highlighted by a panel of immunohistochemical stains in all different components of the tumor. Molecular studies revealed a PIKCA3 mutation, a genetic aberration that has been documented in EMCA, particularly of breast origin. The current case documents for the first time a pcAME with malignant features arising from a spiradenoma and suggests adenomyoepithelioma ex spiradenoma as a possible tumorigenesis pathway of this rare cutaneous tumor.

Incisional biopsy critical in obtaining definitive diagnosis in a clinically challenging case.

Tissue-sparing biopsy techniques are frequently used in clinical practice but can result in misdiagnosis of large, clinically challenging lesions. We present a case of a 70-year-old man with hidradenocarcinoma of the left chin, a diagnosis that was delayed owing to repeated superficial biopsies that were negative for disease. Diagnosis was ultimately obtained via an incisional biopsy. We discuss the clinical features of hidradenocarcinoma and why this diagnosis can be easily missed with superficial biopsies. It is important that dermatologists consider incisional biopsies in the workup of clinically challenging lesions for which malignancy is considered.