Frozen Section Histoanatomy of the Peritarsal Eyelid.

BACKGROUND: Mohs surgery of eyelid skin cancers requires detailed knowledge of anatomy for precise surgery and accurate evaluation of histology. OBJECTIVE: To review the histology of the peritarsal eyelid using frozen sections as encountered intraoperatively by Mohs surgeons. METHODS: The authors review the literature describing the anatomy and histology of the peritarsal eyelid from the lens of a Mohs surgeon. Histology from select Mohs cases is used to frame the discussion of the microanatomy of this region. RESULTS: The peritarsal eyelids contain a unique mixture of skin, muscle, tarsus, glandular tissue, and conjunctiva. The histologic appearance of many of these structures differs from skin found outside of this anatomic region. Tumors of the eyelid and periocular region may mimic normal histologic structures found within the peritarsal eyelid. CONCLUSION: The peritarsal eyelids have unique anatomy and associated histologic structures. Knowledge of the detailed histoanatomy is required for confident execution of Mohs surgery in this anatomic region.

A call for nail clipping histopathology to become an essential component of the routine evaluation of melanonychia: Benefitting patients as a triage and surgical planning maneuver.

We call on dermatologists and dermatopathologists to include nail clipping histopathology as an essential component of the routine evaluation of melanonychia. This manuscript demonstrates a case where an adult woman with broad melanonychia of the right thumbnail declined a nail matrix biopsy, but was amenable to a nail clipping.The nail clipping showed pigmentation, melanocyte remnants, and small cavities in the nail plate. These features have been published previously by our group as a clue to nail unit melanoma within nail clippings.This patient was rapidly triaged for nail matrix biopsy, which demonstrated nail unit melanoma in situ. Every patient with melanonychia can benefit from a nail clipping by examination of the location of the pigmentation within the nail plate for surgical planning, and if melanocyte remnants are detected, the nail clipping also serves as a rapid triage mechanism for nail matrix biopsy to evaluate for nail unit melanoma. Fontana-stained sections will highlight the pigmentation in the nail plate, and its location in the nail plate can easily be described by the dermatopathologist. Nail clippings performed in the setting of clinically apparent melanonychia may show helpful histopathologic findings of pigmented fungi, hemorrhage, external pigmentation, features of other pigmented nail unit tumors, as well as other entities. Nail clipping histopathology can provide extensive information in the evaluation of melanonychia with minimal discomfort for a patient, and little disruption to a physician's clinic flow. With this additional case of a nail unit melanoma diagnosed after initial concern found in a nail clipping, as well as other information in the literature, it is clear that melanocyte remnants found in nail clippings are reliable concerning features related to nail unit melanoma in adults. With knowledge of these histopathologic features in nail clippings and the significance of melanocyte remnants, the dermatopathologist can play a crucial role in the use of a nail clipping as a life-saving diagnostic maneuver. Accordingly, given the potential benefit to patients in this setting, as well as other uses of a nail clipping in the evaluation of melanonychia, we call on dermatologists and dermatopathologists to innovate the routine evaluation of melanonychia through the routine employment of nail clippings for histopathologic evaluation.

Clinicohistopathologic challenges and traps in the diagnosis of nail unit melanoma.

Melanoma of the nail apparatus is challenging to diagnose for both dermatologists and dermatopathologists. Misdiagnosis or delayed diagnosis of nail unit melanoma can have fatal consequences and legal ramifications. This review educates dermatopathologists on challenges and traps they should be aware of to avoid misdiagnosis of nail unit melanoma. We present illustrative difficult cases that introduce several themes regarding challenges in the diagnosis of nail unit melanoma: specimens with subtle histopathologic findings, challenges in immunoperoxidase interpretation, and how clinical knowledge and surgical procedural knowledge are mandatory to make the diagnosis. Dermatopathologists will be aware of when and how to suspect nail unit melanoma in unusual circumstances.

Local Recurrence Rates After Excision of Desmoplastic Melanoma: A Systematic Review and Meta-Analysis.

BACKGROUND: Few prospective studies have evaluated local recurrence rates (LRR) after excision of desmoplastic melanoma (DM); however, several retrospective studies have reported high LRR. OBJECTIVE: To determine LRR after excision of DM and evaluate factors affecting LRR. MATERIALS AND METHODS: Systematic review of the PubMed, Embase, and Web of Science databases was performed to identify studies reporting local recurrence after excision of DM with conventional wide local excision (WLE), Mohs micrographic surgery (MMS), or staged excision (SE). Meta-analysis was performed to calculate summary LRR and pooled risk ratios (RR). RESULTS: Literature search identified 4 studies evaluating MMS or SE (total n = 61 DM). 53 studies assessed WLE ( n = 3,080) and were analyzed quantitatively. The overall LRR after WLE of DM was 21% (95% CI, 0.16-0.28; n = 2,308). Local recurrence rate was higher with positive/unknown histologic excision margins (49%, 95% CI, 0.25-0.74; n = 91) versus negative histologic margins (11%, 95% CI, 0.07-0.17; n = 1,075; [ p < .01]). Neurotropism was also associated with increased LRR (RR, 1.79; 95% CI, 1.34-2.38, p < .01; n = 644). CONCLUSION: DM has high LRR after WLE. Local recurrence risk was greatest with positive excision margins, indicating the importance of achieving negative microscopic margins. Greater study of MMS and SE for DM is required.

Lichen-planus-pemphigoides-like reaction to PD-1 checkpoint blockade.

BACKGROUND: Programmed cell death protein (PD-1) and programmed death-ligand 1 (PD-L1) inhibition checkpoint blockade leads to various cutaneous adverse reactions, including bullous pemphigoid and lichen-planus-like reactions. However, lichen planus pemphigoides (LPP), manifesting histopathologic features of both lichen planus and bullous pemphigoid, has more rarely been associated with immunotherapy. METHODS: The clinical and histopathologic findings of three patients were examined, and a review of cases of LPP and bullous lichen planus secondary to PD-1 inhibitor therapy was performed. RESULTS: Three patients (two with advanced non-small-cell lung adenocarcinoma and the third with metastatic breast cancer) presented with both lichenoid eruptions and bullae. Biopsy of the lesions revealed lichenoid tissue reactions in all three patients. Together with the histopathologic findings, direct immunofluorescence (DIF) showing linear C3 and IgG deposition and positive enzyme-linked immunosorbent assay (ELISA) showing BP180 positivity supported a diagnosis of LPP in two patients. The third patient in our series also showed confirmatory ELISA testing supporting LPP. CONCLUSIONS: Lichen planus pemphigoides is a distinct cutaneous toxicity to checkpoint inhibitor therapy illustrates a possible pathogenic mechanism and the importance of dermatopathology recognition to render an accurate diagnosis.

Two Cases of Insulin-Derived Amyloidosis With Acanthosis Nigricans-Like Changes.

ABSTRACT: Insulin-derived amyloidosis (AIns) is a rare iatrogenic subtype of cutaneous amyloidosis occurring at frequent insulin injection sites. Here, we describe 2 cases of AIns accompanied by acanthosis nigricans (AN)-like changes, a rare finding which has been reported fewer than 5 times in the literature. We also report the first case of an AIns nodule being misdiagnosed as a keloid. Both of our patients presented with asymptomatic, hyperkeratotic, pigmented plaques at frequent insulin injection sites, and histopathologic examination showed (1) nodular aggregates of amyloid demonstrating apple-green birefringence with Congo red staining and (2) AN-like features, such as epidermal papillomatosis, hyperkeratosis, and hyperpigmentation. Accurate diagnosis of AIns is crucial, because repeated insulin injection into a nodule can impair glycemic control. However, misdiagnosis is common, as observed with our second patient, whose AIns nodule was misdiagnosed by an outside provider as a keloid, perhaps because of the presence of AN-like features. Our case report adds to the limited but growing body of literature on AIns and significantly increases the number of reported cases of AIns with AN-like features, an even rarer phenomenon.

Cutaneous Ganglioneuromas With Overlying Epidermal Hyperplasia: A Case Series Presentation and Proposal of Potential Etiopathogenesis.

ABSTRACT: Cutaneous ganglioneuromas (GNs) are exceptionally uncommon tumors, and many reported cases describe association with overlying epidermal hyperplasia that may be interpreted as seborrheic keratosis (SK) or SK-like proliferation. We report 5 cases of cutaneous GN in adult patients; all of which were discovered incidentally in the immediate vicinity of epidermal hyperplasia. A review of the literature demonstrates the current-although likely imperfect-understanding of the etiopathogenesis of both SK and GN in the skin. We explore the putative pathophysiologies of other common, well-characterized skin lesions and, taking them into account, provide rationale for the coexistence of cutaneous GN with overlying SK and SK-like epidermal changes. However, we ultimately acknowledge a dilemma of causality and, given the rarity of their co-occurrence, objectively question whether occasional cameo appearances by GN lying subjacent to SK and SK-like hyperplasia may be due merely to chance.

Histologic features of melanoma associated with germline mutations of CDKN2A, CDK4, and POT1 in melanoma-prone families from the United States, Italy, and Spain.

BACKGROUND: CDKN2A, CDK4, and POT1 are well-established melanoma-susceptibility genes. OBJECTIVE: We evaluated melanoma histopathology for individuals with germline mutations of CDKN2A, CDK4, and POT1. METHODS: We assessed histopathology for melanomas diagnosed in melanoma-prone families (≥2 individuals with melanoma) from the United States, Italy, and Spain. Comparisons between mutation carriers and noncarriers (no mutation) were adjusted for age, sex, Breslow depth, and correlations among individuals within the same family. RESULTS: Histologic slides were evaluated for 290 melanomas (139 from 132 noncarriers, 122 from 68 CDKN2A carriers, 10 from 6 CDK4 carriers, and 19 from 16 POT1 carriers). Superficial spreading was the predominant subtype for all groups. Spitzoid morphology (>25% of tumor) was observed in 10 of 15 invasive melanomas (67%) from POT1 carriers (P < .0001 vs noncarriers). This finding was independently confirmed by 3 expert melanoma dermatopathologists in 9 of 15 invasive melanomas (60%). In situ and invasive melanomas from CDKN2A and CDK4 carriers were histologically similar to melanomas from noncarriers. LIMITATIONS: Limited sample sizes for rare melanoma-susceptibility syndromes (CDK4, POT1). CONCLUSION: Spitzoid morphology was associated with POT1 mutations suggesting that telomere dysfunction (POT1 mutations) may contribute to spitzoid differentiation in melanocytic tumors.

There is fat in this sclerosis: A case report of sclerotic lipoma and review of the literature.

Sclerotic lipomas, a lipoma variant, are benign subcutaneous tumors, so-named because of their resemblance to sclerotic fibromas. Previous literature has suggested that these tumors may show a predilection for middle-aged adult males. We report an unusual case of a sclerotic lipoma diagnosed on the scalp of a 66-year-old female. The patient presented to the outpatient clinic with a 3- to 4-year history of an enlarging and irritated 2.6-cm nodule on the anterior crown of the scalp, clinically thought to be a pilar cyst. Histopathological examination from the excisional specimen revealed a well-circumscribed dermal to subcutaneous tumor with ample sclerotic collagen bundles, an increased number of CD34 positive spindled cells, and prominent S-100 positive mature adipocytes comprising greater than 50% of the tumor. We present this case given its atypical clinical and histopathological presentation, review the literature of sclerotic lipomas, and discuss the differential diagnosis to raise awareness of this rare entity.

Persistent Agminated CD30+ Lymphoproliferative Disorder.

Lymphomatoid papulosis (LyP) is a chronic skin condition, characterized by recurrent eruptions of papules and nodules with or without central necrosis that spontaneously resolve. This condition was originally described by Macaulay in 1968 as a self-healing rhythmical paradoxical eruption that was clinically benign yet histologically malignant.1 Clinically, it is defined by papules that wax and wane, are generally less than 1cm in diameter, and heal spontaneously after 6­8 weeks with subsequent scarring.2

Follicular induction and CK20+ Merkel cells overlying cutaneous focal mucinosis.

BACKGROUND: Cutaneous focal mucinosis (CFM) or focal dermal mucinosis is a benign reactive process categorized as a primary mucinosis. Skin biopsy is essential for diagnosis, as the clinical appearance is often non-specific. Follicular induction is a phenomenon whereby the epidermis is induced by an underlying process to form primitive or mature hair follicles, and is commonly seen overlying dermatofibromas. Follicular induction has been rarely described in CFM. METHODS: We performed a retrospective histological review of lesions of CFM confirmed by skin biopsy from 2010 to 2015 in our department. RESULTS: We found that 11% (11/98) of CFM lesions showed follicular induction. Cytokeratin 20 (CK20) immunostaining was performed on all 11 of these biopsies that showed follicular induction and highlighted an increased density of CK20+ Merkel cells within the basaloid epidermal proliferations. CONCLUSION: As superficial basal cell carcinomas (BCC) often show a mucinous stroma around the basaloid islands, CFM with follicular induction may closely mimic a BCC histologically, particularly in superficial shave biopsies. Therefore, it is important that dermatopathologists be aware of this phenomenon. Furthermore, CK20+ staining within the basaloid epithelial proliferations may be helpful in differentiating CFM with follicular induction from a BCC.

NRAS Q61R and BRAF G466A mutations in atypical melanocytic lesions newly arising in advanced melanoma patients treated with vemurafenib.

BACKGROUND: BRAF inhibition has improved overall survival in patients with BRAF mutant melanoma, but this is associated with a range of known and predictable cutaneous side effects, including squamous cell carcinomas associated with RAS mutations. METHODS: We identified three severely dysplastic nevi, one atypical intraepidermal melanocytic proliferation, and four melanoma in situ lesions, newly arising in four patients undergoing treatment with vemurafenib. To characterize mutations in these atypical melanocytic lesions, we used a custom iPlex panel detecting 74 mutations in 13 genes known to play a role in melanoma pathogenesis. RESULTS: We identified an NRAS mutation at codon 61 (Q61R) and a rare BRAF exon 11 mutation (G466A) in atypical melanocytic lesions that arose in patients treated with vemurafenib. CONCLUSION: There appears to be development or accelerated growth of atypical melanocytic lesions in the setting of BRAF inhibition. Our results underscore the need for careful surveillance for melanocytic lesions in patients on BRAF inhibitor therapy and shed light on potential mechanisms for melanoma pathogenesis in the context of BRAF pathway blockade. Further studies are warranted to show a causal relationship.

Lupus-like cutaneous reaction following pembrolizumab: An immune-related adverse event associated with anti-PD-1 therapy.

PD-1 (programmed cell death-1) inhibitors, used to treat metastatic melanoma and other malignancies, are associated with development of immune-related adverse events in the skin. Such reactions include morbilliform eruptions, vitiligo, alopecia areata and bullous pemphigoid. In this report, we describe a patient who developed a lupus-like cutaneous reaction in the setting of pembrolizumab therapy for metastatic melanoma, adding to the spectrum of reactions which may be observed in association with PD-1 inhibitor therapy.

MART-1-labeled melanocyte density and distribution in actinic keratosis and squamous cell cancer in situ: Pagetoid melanocytes are a potential source of misdiagnosis as melanoma in situ.

BACKGROUND: Actinic keratosis (AK) and squamous cell carcinoma in-situ (SCCIS) within or near melanoma in situ (MIS) can complicate diagnosis due to overlapping clinical and microscopic features. This study aimed to describe basilar melanocyte density and pagetoid spread in AK and SCCIS for improved diagnostic accuracy. METHODS: A total of 22 AK and 22 SCCIS biopsies containing a margin of uninvolved epidermis were immunostained with MART-1 (melanoma antigen recognized by T-cells 1). The basilar melanocyte:keratinocyte ratio and the number and distribution of pagetoid melanocytes were compared in AK, SCCIS, and uninvolved epidermis. An in-vitro human skin model was created to assess the impact of keratinocyte atypia on melanocyte distribution. RESULTS: The median basilar melanocyte:keratinocyte ratio in SCCIS (1:11.49) was lower than in uninvolved epidermis (1:5.59, P = 0.0011), and the ratio in AK (1:6.94) was similar to uninvolved epidermis (P = 0.987). Pagetoid melanocytes were absent in perilesional skin but common in AK (21/22, P < 0.0001) and SCCIS (22/22, P < 0.0001). Pagetoid melanocytes at or above the mid-spinous layer were more common in SCCIS (21/22) vs AK (7/22, P < 0.0001). Pagetoid melanocytes were present in the in-vitro skin model made with neoplastic but not normal keratinocytes. CONCLUSIONS: Pagetoid melanocytes in AK and SCCIS should be interpreted with caution to avoid overdiagnosis of MIS.

Angiomatoid and desmoplastic Spitz nevus presenting as a keloidal nodule.

Angiomatoid and desmoplastic Spitz nevi are rare histologic variants of Spitz nevi that present most frequently on the extremities of children and young adults. Although Spitz nevi are clinically heterogeneous, one presenting as a keloidal nodule has not been previously published. We present a case of an angiomatoid and desmoplastic Spitz nevus clinically akin to a keloid on an African-American teenager and describe its unique histopathologic features.

An independent validation of a gene expression signature to differentiate malignant melanoma from benign melanocytic nevi.

BACKGROUND: Recently, a 23-gene signature was developed to produce a melanoma diagnostic score capable of differentiating malignant and benign melanocytic lesions. The primary objective of this study was to independently assess the ability of the gene signature to differentiate melanoma from benign nevi in clinically relevant lesions. METHODS: A set of 1400 melanocytic lesions was selected from samples prospectively submitted for gene expression testing at a clinical laboratory. Each sample was tested and subjected to an independent histopathologic evaluation by 3 experienced dermatopathologists. A primary diagnosis (benign or malignant) was assigned to each sample, and diagnostic concordance among the 3 dermatopathologists was required for inclusion in analyses. The sensitivity and specificity of the score in differentiating benign and malignant melanocytic lesions were calculated to assess the association between the score and the pathologic diagnosis. RESULTS: The gene expression signature differentiated benign nevi from malignant melanoma with a sensitivity of 91.5% and a specificity of 92.5%. CONCLUSIONS: These results reflect the performance of the gene signature in a diverse array of samples encountered in routine clinical practice. Cancer 2017;123:617-628. © 2016 American Cancer Society.

Topical resiquimod can induce disease regression and enhance T-cell effector functions in cutaneous T-cell lymphoma.

Early-stage cutaneous T-cell lymphoma (CTCL) is a skin-limited lymphoma with no cure aside from stem cell transplantation. Twelve patients with stage IA-IIA CTCL were treated in a phase 1 trial of 0.03% and 0.06% topical resiquimod gel, a Toll-like receptor 7/8 agonist. Treated lesions significantly improved in 75% of patients and 30% had clearing of all treated lesions. Resiquimod also induced regression of untreated lesions. Ninety-two percent of patients had more than a 50% improvement in body surface area involvement by the modified Severity-Weighted Assessment Tool analysis and 2 patients experienced complete clearing of disease. Four of 5 patients with folliculotropic disease also improved significantly. Adverse effects were minor and largely skin limited. T-cell receptor sequencing and flow cytometry studies of T cells from treated lesions demonstrated decreased clonal malignant T cells in 90% of patients and complete eradication of malignant T cells in 30%. High responses were associated with recruitment and expansion of benign T-cell clones in treated skin, increased skin T-cell effector functions, and a trend toward increased natural killer cell functions. In patients with complete or near eradication of malignant T cells, residual clinical inflammation was associated with cytokine production by benign T cells. Fifty percent of patients had increased activation of circulating dendritic cells, consistent with a systemic response to therapy. In summary, topical resiquimod is safe and effective in early-stage CTCL and the first topical therapy to our knowledge that can induce clearance of untreated lesions and complete remissions in some patients. This trial was registered at www.clinicaltrials.gov as #NCT813320.

Clinical factors associated with subclinical spread of in situ melanoma.

BACKGROUND: Subclinical spread of in situ melanoma occurs at a wide frequency, ranging from 12% to 71%. OBJECTIVE: To identify clinical factors associated with subclinical spread of in situ melanoma. METHODS: We used a retrospective, cross-sectional study of 674 consecutive in situ melanomas to examine 627 patients treated with Mohs surgery and melanoma antigen recognized by T cells 1 immunostaining. The presence of subclinical spread was correlated with clinical characteristics. Univariate and multivariate logistic regression analyses were performed to generate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Both univariate and multivariate analyses demonstrated significantly increased odds for subclinical spread of in situ melanomas when they were located on the head or neck, at acral sites, or on the pretibial leg (OR 1.97, 95% CI 1.41-3.40); in persons with a history of prior treatment (OR 2.77, 95% CI 1.74-4.420); melanomas of preoperative size >1 cm (OR 1.74, 95% CI 1.23-2.46, P = .002); or in persons ≥60 years old (OR 1.47, 95% CI 1.01-2.13, P = .042). A count prediction model demonstrated that the risk for subclinical spread increased with the number of clinical risk factors. LIMITATION: We used a single-site, retrospective study design. CONCLUSION: Clarifying the risk factors for subclinical spread might help to refine triage of in situ melanomas to the appropriate surgical techniques for margin assessment prior to reconstruction.