Perineural Infiltration: A Comprehensive Review of Diagnostic, Prognostic, and Therapeutic Implications.

ABSTRACT: Perineural infiltration refers to a neoplastic cell involvement in, around, and through the nerves. It is considered as one of the neoplastic dissemination pathways. Thus, its identification is crucial to establish the prognosis of some malignant skin neoplasms, such as squamous cell carcinoma, and explains the locally aggressive behavior of cutaneous neoplasms, such as microcystic adnexal carcinoma. We have conducted a review of malignant and benign skin tumors in which perineural infiltration has been described, and we also discuss some histopathological findings that may simulate perineural infiltration.

Nectin-4 expression in a subset of cutaneous adnexal carcinomas: A potential target for therapy with enfortumab vedotin.

BACKGROUND: Enfortumab vedotin (EV) is an antibody-drug conjugate directed against Nectin-4 that is used to treat urothelial carcinoma. Nectin-4 is inherently expressed in the skin and adnexal structures. Since therapeutic options for cutaneous adnexal carcinomas are limited, we sought to evaluate Nectin-4 expression in adnexal carcinomas and benign adnexal neoplasms to identify tumors that are potentially targetable with EV. METHODS: Eight sebaceous carcinomas (seven periocular and one lymph node metastasis), eight digital papillary adenocarcinomas, seven squamoid eccrine ductal carcinomas, eight poromas, eight trichilemmomas, and seven sebaceous adenomas were subjected to immunohistochemical staining for anti-Nectin-4 antibody. H-scores for Nectin-4 expression were calculated. RESULTS: Benign adnexal neoplasms had a significantly lower mean (±SD) Nectin-4 H-score (142.6 ± 39.1) than did the adnexal carcinomas (198 ± 90.8; p = 0.006). Nectin-4 was expressed in 91% (21/23) of adnexal carcinomas. Sebaceous carcinomas frequently exhibited high expression of Nectin-4 (88% [7/8]), with a mean (±SD) H-score (258.1 ± 58.4) significantly higher than those for digital papillary adenocarcinomas (197.5 ± 52.5; p = 0.035) and squamoid eccrine ductal carcinomas (131.4 ± 114.1; p = 0.031). Sebaceous carcinomas also had significantly higher H-scores than did sebaceous adenomas (186.4 ± 25.0; p = 0.013). CONCLUSIONS: Increased Nectin-4 expression in a subset of cutaneous adnexal carcinomas, particularly sebaceous carcinomas, reveals that EV is a potential therapeutic option for these tumors.

Epidemiology, clinical characteristics, treatment, and outcomes of proliferating pilar tumors: A systematic review.

BACKGROUND: Proliferating pilar tumors (PPTs) are rare cutaneous neoplasms arising from hair follicles that have both malignant and metastatic potential. OBJECTIVE: To present a systematic review of the epidemiology, clinical characteristics, and treatment and outcome data on PPTs. METHODS: Using the OVID platform, MEDLINE and Embase were searched from inception until May 26, 2022. All studies that provided original data on PPTs in English were included. References of these studies were also cross-checked to identify any additional relevant articles. Oxford's Levels of Evidence-Based Medicine was used for quality assessment. RESULTS: A total of 114 articles, providing data on 361 cases of PPTs, were included in our synthesis. Every study included was either a case series or case report. The mean age at diagnosis was 61.7. Most patients in the synthesis were female (71%), and the majority of cases occurred on the scalp (73.1%). The presence or absence of cytological atypia was only reported in one-third of the cases; 36.8% of cases were classified as malignant and 7.5% metastasized. Although no lesions treated with Mohs micrographic surgery required adjuvant radiation and only one reported recurrence occurred after Mohs surgery, there is insufficient data to make conclusions on a superior treatment modality. LIMITATIONS: All studies in this review were either case reports or case series. CONCLUSIONS AND RELEVANCE: Our study supports the notion that PPTs occur most commonly on the scalp of elderly female patients. Moreover, our findings confirm that PPT is capable of demonstrating aggressive biology and metastasis. Given the lack of uniformity in histologic description, pathologists should be encouraged to comment on the presence and degree of cytological atypia when reporting cases of rare neoplasms such as the PPT. Greater consensus on diagnosis and classification as well as more robust data is needed regarding optimal management.

Proliferating Pilar Tumors in the Scalp Over a Period of 23 Years in a General Hospital in Mexico City.

BACKGROUND: Proliferating pilar tumors are an unusual skin tumor, and they have a cystic component with trichilemmal keratinization and epithelial proliferation. These arise from the outer root sheath of hair follicles. It mainly affects women. The scalp is the most affected area. Diagnosis can be made by biopsy. Surgical excision is the best treatment option. OBJECTIVE: Report the frequency of proliferating pilar tumors in the scalp in general hospital in Mexico over a period of 23 years. METHODS: The authors reviewed the database of the dermatopathology service of the General Hospital "Dr Manuel Gea González" from 1999 to August 2022, selecting diagnosticated cases of proliferating pilar tumor, pilar cyst, trichilemmal cyst, or proliferating trichilemmal cyst in the scalp. RESULTS: The authors discovered 17 cases, 13 were women, the average age was 54.9 years, all the tumors affecting the scalp, and just 3 cases were reported as malignant. CONCLUSION: In comparison with the existing data, the authors can observe that most of their patients were women and the scalp is the most affected area. Most did not present associated symptoms. As the authors can see, most are benign and long-lasting: however, the authors cannot ignore that a small percentage can be malignant.

Atypical Melanocytic Matricoma: A Case Report with Molecular Studies.

ABSTRACT: Melanocytic matricoma is a rare benign pilar tumor characterized by matrical differentiation and interspersed dendritic melanocytes. It may show cellular atypia and brisk mitotic activity. Histological characterization of some lesions may be difficult. In addition, because the reported cases are few and have limited follow-up, there is insufficient experience to define outcome-based criteria for malignancy. Some cases of melanocytic matricoma with more prominent atypia have been reported as malignant, but their clinical behavior is uncertain. We present a melanocytic matricoma with interspersed benign dendritic melanocytes, but moderate basaloid atypia, focally brisk mitotic activity, and atypical mitoses. Despite the apparently good delimitation of this tumor, higher magnification revealed a slightly irregular border. However, overt malignant features such as necrosis, frank asymmetry, deep infiltration, and ulceration were not present. This tumor showed a complex aberrant genomic profile with multiple whole chromosomes or chromosomal arms, losses, and duplications. The tumor mutational burden was high. A loss-of-function alteration in CDKN2A and a loss-of-function mutation in TP53 were also present. This unexpected molecular profile contrasts with the relatively bland histology of the tumor and is in line with the difficulties in microscopic differential diagnosis between melanocytic matricoma and an indolent malignant pilomatrical tumor. We suggest that molecular studies and longer follow-up periods may help to further understand and more precisely categorize borderline pilomatrical tumors with melanocytic hyperplasia.

Periocular Microcystic Adnexal Carcinoma: A Case Report and a Major Review.

PURPOSE: To describe a patient with periocular microcystic adnexal carcinoma (MAC) and to review the clinical presentation, systemic work-up, histopathologic features, and outcome of all previously reported periocular MAC. METHODS: A major literature review. PubMed/MEDLINE and Google Scholar databases were searched for all well-documented cases of periocular MAC. RESULTS: The final analysis yielded 93 patients with MAC, 48 (52%) females, 39 (42%) males, and 6 with sex not specified (6%) with an average age of 56 years (range 3 days-95 years). Most tumors were localized to the eyebrow (26/93, 28%) and lower eyelid (20/93, 22%). Of patients with known information, MAC most commonly presented as a nodule (37/68, 54%) or plaque (20/68, 29%) with poorly-defined margins (20/51, 39%) and distortion of eyelid margin (13/51, 25%). Orbital involvement at any point of the disease course was seen in 20 of 93 (22%) patients. An accurate histopathologic diagnosis on initial biopsy was made in 25 of 70 (36%) cases. Initial management included surgical excision (47/93, 51%), Mohs micrographic surgery (17/93, 18%), and excision with frozen section control of margins (8/93, 9%). Aggressive or recurrent MAC was managed with multimodal therapies, including adjuvant radiation (10/34, 29%). The average follow-up after the last treatment was 3 years (median 2, range 0.2-20 years). In total, 33 of 86 (38%) tumors recurred, and 6 of 87 (7%) metastasized. Disease-related mortality occurred in 3 of 79 (4%) of patients. CONCLUSIONS: Periocular MAC is frequently misdiagnosed on initial biopsy and has a tendency for recurrence and locally aggressive behavior, highlighting the importance of accurate timely diagnosis, and appropriate management.

Genetics of adnexal tumors: An update.

Cutaneous adnexal tumors form a vast heterogeneous group that include frequent entities that are mostly benign, as well as rare tumors that are occasionally malignant. In contrast to cutaneous tumors arising from the interfollicular epidermis that develop as a result of accumulation of UV-induced DNA damage (basal cell carcinoma, squamous cell carcinoma), the oncogenesis of adnexal tumors is related to a broad spectrum of genetic mechanisms (e.g., point mutation, fusion genes, viral integration, etc.). In this setting, specific and recurrent genetic alterations have been progressively reported, and these allow better classification of these entities. For certain of them, immunohistochemical tools are now available, enabling precise integrated histological and molecular diagnosis since certain entities are linked to well-defined alterations. In this context, we aim in this review to summarize the main molecular tools currently available for the classification of adnexal tumors.

Sebaceous carcinoma epidemiology, associated malignancies and Lynch/Muir-Torre syndrome screening in England from 2008 to 2018.

BACKGROUND: Sebaceous carcinomas (SC) may be associated with the cancer predisposition syndrome Muir-Torre/Lynch syndrome (MTS/LS), identifiable by SC mismatch repair (MMR) screening; however, there is limited data on MMR status of SC. OBJECTIVE: To describe the epidemiology of SC, copresentation of other cancers, and population level frequency of MMR screening in SC. METHODS: A population-based retrospective cohort study of SC patients in the National Cancer Registration and Analysis Service in England. RESULTS: This study included 1077 SC cases (739 extraocular, 338 periocular). Age-standardized incidence rates (ASIR) were higher in men compared with women, 2.74 (95% CI, 2.52-9.69) per 1,000,000 person-years for men versus 1.47 person-years (95% CI, 1.4-1.62) for women. Of the patients, 19% (210/1077) developed at least one MTS/LS-associated malignancy. MMR immunohistochemical screening was performed in only 20% (220/1077) of SC tumors; of these, 32% (70/219) of tumors were MMR deficient. LIMITATIONS: Retrospective design. CONCLUSIONS: Incorporation of MMR screening into clinical practice guidelines for the management of SC will increase the opportunity for MTS/LS diagnoses, with implications for cancer surveillance, chemoprevention with aspirin, and immunotherapy treatment targeted to MTS/LS cancers.

Radiotherapy of skin adnexal carcinoma.

Skin adnexal carcinomas are rare skin cancer, developing from pilosebaceous, eccrine and apocrine unit. Treatment of localised tumours usually includes surgery and radiotherapy. Indications and modalities of radiotherapy depend on the pathological subtype with a lack of consensus for some histologies. This review summarises the place of radiotherapy in terms of indication, dose and fractionation, volumes to irradiate and discuss ongoing studies.

Mohs micrographic surgery for the treatment of primary cutaneous mucinous carcinoma.

Primary cutaneous mucinous carcinoma (PCMC) is a rare adnexal tumour of the skin. Clinically, it appears as a benign cyst, but it has characteristic histopathology. It is a slow-growing tumour that rarely metastasizes but is associated with significant morbidity due to its high recurrence rate. Standard practice has been to surgically remove it with a wide local excision of 1-2-cm margin. In the last decade, increasing reports of Mohs micrographic surgery (MMS) for the treatment of PCMC have been described. MMS appears to reduce recurrence rates while allowing for more conservative margins. Given the rarity of PCMC, there are no prospective randomized control trials on treatment. This is the largest case series of PCMC treated by MMS to date.

Improved Margin Control of Microcystic Adnexal Carcinoma After Mohs Micrographic Surgery Compared With Wide Local Excision.

BACKGROUND: Microcystic adnexal carcinoma (MAC) is a locally aggressive and deeply infiltrative cutaneous tumor primarily treated with excision; however, there are limited data comparing outcomes by surgical approach. OBJECTIVE: To compare surgical outcomes of MAC treated with Mohs micrographic surgery (MMS) and wide local excision (WLE). METHODS: A 27-year retrospective cohort study of primary MAC was performed. Surgical (i.e. margin status after resection) and recurrence outcomes (including local recurrence [LR], nodal metastases [NM], and distance metastases [DM]) were analyzed by type of surgical approach (MMS and WLE). RESULTS: Sixty-nine MACs were included, of which 34 (49.3%) were treated with MMS and 35 (50.7%) with WLE. All MMS-treated tumors had negative margins after the first surgery attempt. Twenty-one (60.0%) tumors treated with WLE had positive margins after the first surgical attempt and required additional procedures. More tumors treated with WLE developed LR, NM, or DM, although this did not meet statistical significance. LIMITATIONS: Retrospective single institution study. CONCLUSION: Greater than half of MAC tumors treated with WLE had positive margins after the initial surgery and required multiple procedures for complete removal. Real-time complete margin assessment is important for this locally aggressive and infiltrative tumor.

A diagnostic challenge in an atypical variant of microcystic adnexal carcinoma mimicking ulcerative basal cell carcinoma: a case report and brief literature review.

Microcystic adnexal carcinoma (MAC) is a rare adnexal tumor with eccrine and pillar differentiations with a localized and aggressive nature, often misdiagnosed as other dermatoses. The most common clinical manifestations of MAC are yellowish or skin-colored papules, nodules, and plaques. However, in some rare cases an atypical manifestation such as ulceration that resembles malignancies such as basal cell carcinoma (BCC) can also occur. Diagnosis of MAC mainly relies on the aid of histopathology. Due to potential infiltration to other structures such as in perineural invasion, wide surgical excision or Mohs micrographic surgery is the preferred surgical option. We report the case of a 75-year-old male patient with ulcerative lesion on the forehead that clinically resembled BCC in addition to typical dermoscopic findings of BCC. However, histopathology confirmed a diagnosis of MAC, prompting physicians to be more aware of this condition when encountering chronic ulcerative lesions. After wide excision and a 1-year follow-up, the patient exhibited no signs of recurrences and will continue long-term follow-up.

Rare syringoid eccrine carcinoma of the upper lip and nasal base treated with resection and subsequent innovative reconstruction using an Abbé flap, turbinate flaps and three-stage forehead flap: a case report.

BACKGROUND: Although syringoma is a common benign tumour of the sudoriferous gland, there is also an extremely rare malignant form known as syringoid eccrine carcinoma (SEC). SEC usually exhibits slow growth with deep invasion and a frequent tendency to relapse. The treatment of choice is radical wide resection, which poses a difficult reconstructive problem, especially when the tumour is located in the centre of the face. CASE PRESENTATION: In this case, a 70-year-old man was diagnosed with an SEC at the same location as a benign syringoma of the upper lip and nasal base that had undergone primary excision 7 years prior. Primary radical resection was performed with immediate Abbé flap reconstruction. Nevertheless, histology revealed positive margins, and 3 additional re-excisions were needed to achieve clear margins. Four months after the initial resection, the patient had undergone an innovative reconstruction technique including not only the Abbé flap but also a turbinate flap harvested with functional endonasal surgery and a three-stage forehead flap. CONCLUSION: To the best of our knowledge, this is the first case report of a suspect malignant transformation of a benign syringoma after 7 years. In addition, from oncoplastic and reconstructive points of view, the bilateral use of the turbinate flap for reconstructing the intranasal lining of the alar base is unusual, and the use of functional endonasal surgery in nasal reconstruction for reducing the risk of damaging the vascular supply of the flap is innovative.