Hidradenoma papilliferum (HP) is a benign adnexal tumor, commonly affecting the anogenital region of middle-aged women. Clinically, HP typically presents as a slow-growing, unilateral, well-circumscribed, smooth skin-colored cystic dermal nodule, usually growing less than 1 cm in size. Reports of ectopic HP are exceedingly rare but have been identified in areas containing modified apocrine gland structures, most commonly on the head and neck, and have included ceruminous glands of the external ear canal, the Moll glands of the eyelid, mammary glands of the breast, maxillofacial region and areas on the scalp. To the best of our knowledge, there is only one case of ectopic HP located on the external ear canal reported in English literature. We present a second case of draining ectopic HP located on the conchal bowl of the external ear canal.

Pilomatrixoma or pilomatricoma is a benign adnexal neoplasm originating from the hair matrix, the inner sheath of the hair follicle, and the hair cortex. Although it is considered rare in adults, numerous cases have been documented in the literature. We present a case of an elderly male who sought consultation due to a newly appearing nodular lesion on his left forearm. Several benign and malignant entities were included in the original differential diagnosis. High-frequency ultrasonographic features suggested a cystic neoplasm with calcification and mild intralesional vascularity. Ultimately, histopathological examination confirmed the diagnosis of pilomatricoma. In this study, our aim is to review the importance of the available diagnostic tools, such as dermoscopy, and the emerging utility of cutaneous high-frequency ultrasonography. Some rarer pathological variants are also discussed, including perforating, anetodermic, bullous and pigmented pilomatricoma. We hope that exposure to these clinical, dermoscopic, ultrasonographic, and histopathological images will encourage clinicians to consider pilomatricoma in their differential diagnosis when approaching nodular lesions, regardless of location and patient\'s age.

Syringocystadenocarcinoma papilliferum (SCACP) is an exceptionally rare cutaneous adnexal tumor that is infrequently encountered by clinicians worldwide. The tumor typically appears in the older population, affecting patients in their fifth and sixth decades of life without male or female predominance. Patients frequently present with a variable-sized hyperpigmented ulcerative lesion containing an exudate that has a long-standing course of progression from its benign counterpart, Syringocystadenoma papilliferum (SCAP). Additionally, the clinical presentation and morphology of the neoplasm can be easily confused with a variety of other skin cancers, such as squamous cell carcinoma (SCC), basal cell carcinoma (BCC), cutaneous lymphoma, and cutaneous metastasis. Therefore, histopathology and tissue analysis play an essential role in establishing an accurate diagnosis. However, the lesion is so rare that no definitive diagnostic markers have been established yet. We present a case of SCACP localized to the scalp of the patient. Our case study highlights the presence of specific tumor markers that could potentially serve as objective criteria for diagnosis.

The accurate diagnosis of skin adnexal neoplasms is sometimes challenging but is necessary because medical management and follow-up may differ between tumors. GATA6 transcription factor has been identified as a new marker of the upper folliculosebaceous compartment (lower infundibulum, junctional zone and isthmus, and upper sebaceous gland) in the human skin. We aimed to determine the diagnostic accuracy of GATA6 immunostaining to diagnose sebaceous tumors compared with that to diagnose other adnexal and nonadnexal cutaneous neoplasms. We conducted a retrospective, evaluator-nonblinded study comparing the reference standard (diagnosis by an expert dermatopathologist) with GATA6 immunostaining to identify sebaceous tumors in a cohort containing 234 different tumors. The GATA6 expression score was significatively higher in sebaceous than that in nonsebaceous tumors. In addition, tumors originating from the upper hair follicle showed positive results for GATA6 staining; however, they showed lower GATA6 expression scores. Detection of sebaceous tumors using GATA6 positivity had a sensitivity of 95.7% (95% CI, 85.8-99.2), specificity of 80.8% (95% CI, 74.5-85.8), positive predictive value of 55.6% (95% CI, 44.7-65.9), and negative predictive value of 98.7% (95% CI, 95.4-99.8). GATA6 showed similar sensitivity to adipophilin, the reference marker; however, the specificity of GATA6 was higher, as observed in a cohort of 106 tumors enriched in squamous cell carcinomas with clear-cell histology. In addition, GATA6 positivity was assessed in 39 sebaceous carcinomas and compared with epithelial membrane antigen (EMA), CK7, and androgen receptor (AR) staining results. Although CK7 staining displayed lower diagnostic performances, GATA6 staining showed comparable results as EMA and AR. Finally, we found GATA6 expression in skin metastases of gastrointestinal origin, whereas GATA6 was absent in metastases originating from breast or lung cancers. Overall, our work identified GATA6 immunostaining as a new diagnostic tool for sebaceous tumors.

Nasal sebaceous carcinoma is an extremely rare cutaneous malignancy. We present the case of an 86-year-old female who had a skin nodule with surface telangiectasia on the right ala of the nose. The lesion had been removed and has been reconstructed with an advancement rotational flap with a minimal residual defect. Upon histopathological examination, the lesion was diagnosed with sebaceous carcinoma. The patient was followed up because of the high rate of recurrence as well as metastatic potential. No recurrence occurred during 4 years of follow-up, and the patient was unwilling to reconstruct the remaining alar defect. We present a rare skin cancer case that could be encountered during the head and neck examination by oral and maxillofacial surgeons. By reporting this case, we aimed to raise the awareness and familiarize clinicians with these less common lesions.

BACKGROUND: Adnexal skin tumors are diagnostically challenging with few known molecular signatures. Recently, however, YAP1-MAML2 and YAP1-NUTM1 fusions were identified in poroid adnexal skin tumors.
METHODS: Herein, we subjected eight poroid adnexal skin tumors (three poromas and five porocarcinomas) to fusion gene analysis by whole transcriptome sequencing and next-generation DNA sequencing analysis.
RESULTS: YAP1 fusions were identified in six cases. YAP1-NUTM1 fusions were identified in two poromas and three porocarcinomas. A single case of porocarcinoma harbored a YAP1-MAML2 fusion. Two cases were negative for gene fusion. All cases that harbored YAP1-NUTM1 fusions showed nuclear protein in testis (NUT) expression by immunohistochemistry, with NUT being negative in the YAP1-MAML2-positive case. In this case series, we provide a detailed histopathologic description of six YAP1-fused poroid skin tumors, which we show harbor reproducible histopathologic features, to include broad, bulbous tumor tongues with admixtures of basaloid, poroid cells punctuated by squamatized cuticles and ductules, with uniform tumor nuclei featuring frequent grooves and pseudonuclear inclusions.
CONCLUSIONS: Awareness of the characteristic histopathologic features of YAP1-fused poroid adnexal skin tumor is a step toward a more reproducible classification of adnexal skin tumors as well as a step toward targeted therapy for metastatic and/or unresectable examples of this poroid group of neoplasms.

Primary scrotal cancer is a rare urologic malignancy with various histologic subtypes. Management and outcomes are not designed optimally. Surgical excision is the recommended treatment for localized scrotal cancer, with assessment of the margins for disease. Closure of the defect can be performed with primary closure, skin grafts, flaps, or by secondary intention. Analysis of outcomes suggests that high-risk scrotal cancer may have a worse prognosis compared with penile cancer, and low-risk scrotal cancer may have a comparable prognosis. Understanding techniques for management and survival outcomes can help the urologist determine the appropriate course of treatment and improve patient care.

BACKGROUND: Eccrine porocarcinoma is a rare cutaneous tumor arising from the intra-epidermal portion of eccrine sweat glands, the acrosyringium. Histoprognostic studies in large series are rare. Herein, we report a retrospective study of 50 cases.
METHODS: Fifty cases of porocarcinoma were retrieved from a histopathological register. Each histopathological sample was evaluated for the following criteria: presence or absence of dermal invasion, pattern of the infiltrative component (pushing or infiltrative), tumor thickness, lymphovascular emboli, perineural invasion and mitotic index. Clinical data and outcome were also retrieved for each patient.
RESULTS: Mean patient age was 77 years (range: 43-99 years). The mean duration of progression prior to diagnosis was 4 years and 5 months. The 2 most common skin locations were the head (38%) and lower limbs (20%). The lesions showed no specific distinctive clinical features. Six cases were in situ, and 44 were invasive (23 with limited infiltration and 20 with scattered infiltration). Mean tumor thickness was 4.37 mm (range: 0.5 to 20 mm). Neighboring or remote epidermal involvement was noted in 7 cases. Lymphovascular emboli were observed in 3 cases. No cases of neurotropism were observed. The average mitotic index was 6.5 mitoses/high power (×400) field. A mean follow-up of 24.3 months was available for 48 patients. Local recurrence was noted in 5 patients, 4 of whom died from visceral metastases. These 5 cases showed no distinctive clinical features, a scattered pattern of the invasive component, cuticular cells, significant tumor thickness (mean 12.8 mm, range 9-20 mm), and an elevated mitotic index. Two histopathological criteria were significantly associated with a metastatic outcome: scattered pattern of the dermal invasive component (P=0.04) and significant tumor thickness, above 10mm (P<0.01).
CONCLUSIONS: Porocarcinoma is a tumor without any particular clinical criteria to distinguish it from squamous cell carcinoma. The architecture of the invasive component and tumor thickness constitute 2 important histoprognostic criteria.