Amplification of mutant NRAS in melanocytic tumors with features of Spitz tumors

NRAS activating mutations are prevalent in melanocytic neoplasia, occurring in a subset of common acquired melanocytic nevi and approximately 30% of cutaneous melanomas. In this study, we describe a cohort of seven distinctive melanocytic tumors characterized by activating point mutations in codon 61 of NRAS with amplification of the mutant NRAS allele and shared clinicopathologic features. These tumors occurred predominantly in younger patients, with a median age of 20 years (ranging from 6 to 56). They presented as papules on the helix of the ear (four cases) or extremities (three cases). Microscopically, the tumors were cellular, relatively well-circumscribed, compound or intradermal proliferations. The tumor cells often extended into the deep reticular dermis, and involved the superficial subcutaneous fat in some cases. The melanocytes were epithelioid to spindled with moderate amounts of cytoplasm and conspicuous nucleoli. They were arranged in short plexiform fascicles, nests, and cords. Some cases had occasional pleomorphic and multinucleated melanocytes. Rare dermal mitotic figures were present in all cases. The dermis contained thick collagen bundles and minimal solar elastosis. Follow-up data were available for five patients, with a median period of 4.2 years (ranging from 1 to 9 years), during which no recurrences or metastases were reported. Our series highlights a clinicopathologically and molecularly distinctive subset of NRAS-mutated tumors with amplification of the mutant NRAS allele.

Melanoma in infants, caused by a gene fusion involving the anaplastic lymphoma kinase (ALK)

We describe the first cases of pediatric melanoma with ALK fusion gene arising within giant congenital melanocytic nevi. Two newborn boys presented with large pigmented nodular plaques and numerous smaller satellite nevi. Additional expansile nodules developed within both nevi and invasive melanomas were diagnosed before 10 months of age in both boys. Oncogenic driver mutations in NRAS and BRAF were absent in both cases. Instead, oncogenic ZEB2::ALK fusion genes were identified in both the nevus and melanoma developing within the nevus. In both cases, tumors were noted by ultrasound in utero, demonstrated significant nodularity at birth, and progressed to melanoma in the first year of life suggesting that congenital nevi with ALK fusion genes may behave more aggressively than those with other mutations. As ALK kinase inhibitors are effective against a range of tumors with similar ALK fusion kinases, identifying ALK fusion genes in congenital melanocytic nevi may provide an opportunity for targeted therapy.

Histopathologic and Genetic Findings in Atypical Spindle Cell/Pleomorphic Lipomatous Tumors and Atypical Pleomorphic Fibromas

BACKGROUND

Spindle cell lipomas, pleomorphic lipomas (SCL/PLs) and pleomorphic fibromas (PF) are tumors with loss of retinoblastoma (RB). The latest World Health Organization classification includes a category of atypical spindle cell/pleomorphic lipomatous tumors (ASPLT) that encompasses tumors in this spectrum that show atypical histopathologic features. We have observed PFs that show similar atypical features.

METHODS

Cases of SCL/PL and PF with atypical features were collected from tissue archives between 2010-2019. Genetic alterations were investigated using array comparative genomic hybridization (aCGH).

RESULT

Of 15 cases found, most tumors were dermal-based with fibrocytic or fibroadipocytic appearance and occasional lipoblasts. All cases had a high proliferation index with atypical mitotic figures in 71% of cases. Chromosome 13q loss was present in all cases with CGH data. Additional recurrent chromosomal losses included 17p, 16q, 17q, 20p, 4, and 10. No recurrence was found in limited follow up.

CONCLUSIONS

ASPLTs are characterized by loss of RB, prominent nuclear pleomorphism, mitotic activity including atypical mitotic figures, and genomic instability with multiple chromosomal aberrations. A similar group of tumors with these histopathologic features lacks lipomatous differentiation, and we propose the diagnosis of atypical PF as a fibromatous variant of ASPLT. Limited clinical follow up appears benign.

Skin and Mucosal Manifestations in NEMO Syndrome: A Case Series and Literature Review

OBJECTIVES

To characterize the skin and mucosal findings of NEMO syndrome.

METHODS

Retrospective review of clinical characteristics from a cohort of two families with mutations in IKBKG (the NEMO-encoding gene). A literature review identified 86 studies describing 192 patients with IKBKG mutations whose data were also included.

SETTING

Single center with literature review.

PARTICIPANTS

Patients with mutations in IKBKG from our center and reported in the literature.

MAIN OUTCOMES AND MEASURES

Skin and mucosal characteristics of patients with NEMO syndrome.

RESULTS

In addition to ectodermal dysplasia and recurrent infections, male patients had findings of ichthyosis, palmoplantar keratoderma, and inflammatory skin diseases. Both male and female patients had mucocutaneous ulcers and slow-to-heal chronic wounds. In combination with patients from the literature, 59% (85/144) of males had ectodermal dysplasia with anhidrosis (EDA) features, and 8% and 10% (12/144; 6/63) of males and females had dental findings, respectively. 4% (6/144) of males and 32% (20/63) of females had mucocutaneous ulcers. Ichthyosis/xerosis was present in 15% of males (21/144) but only 2% (1/63) females. Similarly, 13% (18/144) of male patients presented with dermatitis while this was reported in only 2% (1/63) of females.

CONCLUSIONS

Our results both confirm and expand upon the known spectrum of mucocutaneous findings in NEMO syndrome. Further genetic studies are needed to correlate specific mutations to clinical and morphologic subtypes.

Cicatricial Pemphigoid Brunsting-Perry Variant Masquerading as Neutrophil-Medicated Cicatricial Alopecia

A 72-year-old male presented with scarring alopecia on the scalp vertex, multiple crusted plaques on the hairline, and a history of vesicular eruption on the face. The scalp showed crusted plaques with loss of follicular ostia. No follicular pustules or compound follicles were present. An initial transverse scalp biopsy showed perifollicular neutrophils, lymphocytes, and plasma cells along with dermal fibrosis. Focal epidermal/dermal and follicular/adventitial dermal clefts were apparent but were thought to be secondary to fibrosis, and the biopsy was interpreted to represent a neutrophil-mediated cicatricial alopecia. Concurrently, direct immunofluorescence (DIF) analysis demonstrated linear junctional deposition of IgG and C3. A repeat scalp biopsy revealed more prominent epidermal/dermal clefts, fibrosis, mixed infiltrate with neutrophils, lymphocytes, histiocytes and plasma cells and prominent follicular/adventitial dermal clefts with perifollicular neutrophils. Given the combination of clefts, perijunctional neutrophils, and positive DIF findings, it became clear that this eruption represented the Brunsting-Perry variant of cicatricial pemphigoid. Here, we illustrated that a neutrophil-rich form of cicatricial pemphigoid can masquerade as a neutrophil-mediated scarring alopecia. In evaluating a specimen suspected to be a neutrophil-mediated scarring alopecia, one should be alert to the presence of subepidermal and perifollicular clefting, and consider cicatricial pemphigoid. This article is protected by copyright. All rights reserved.

BRAFV600E induces reversible mitotic arrest in human melanocytes via microrna-mediated suppression of AURKB

Benign melanocytic nevi frequently emerge when an acquired BRAFV600E mutation triggers unchecked proliferation and subsequent arrest in melanocytes. Recent observations have challenged the role of oncogene-induced senescence in melanocytic nevus formation, necessitating investigations into alternative mechanisms for the establishment and maintenance of proliferation arrest in nevi. We compared the transcriptomes of melanocytes from healthy human skin, nevi, and melanomas arising from nevi and identified a set of microRNAs as highly expressed nevus-enriched transcripts. Two of these microRNAs-MIR211-5p and MIR328-3p-induced mitotic failure, genome duplication, and proliferation arrest in human melanocytes through convergent targeting of AURKB. We demonstrate that BRAFV600E induces a similar proliferation arrest in primary human melanocytes that is both reversible and conditional. Specifically, BRAFV600E expression stimulates either arrest or proliferation depending on the differentiation state of the melanocyte. We report genome duplication in human melanocytic nevi, reciprocal expression of AURKB and microRNAs in nevi and melanomas, and rescue of arrested human nevus cells with AURKB expression. Taken together, our data describe an alternative molecular mechanism for melanocytic nevus formation that is congruent with both experimental and clinical observations.

Early-life inflammation primes a T helper 2 cell-fibroblast niche in skin

Inflammation early in life can prime the local immune milieu of peripheral tissues, which can cause lasting changes in immunological tone that confer disease protection or susceptibility¹. The cellular and molecular mechanisms that prompt changes in immune tone in many nonlymphoid tissues remain largely unknown. Here we find that time-limited neonatal inflammation induced by a transient reduction in neonatal regulatory T cells causes a dysregulation of subcutaneous tissue in mouse skin. This is accompanied by the selective accumulation of type 2 helper T (T_H2) cells within a distinct microanatomical niche. T_H2 cells are maintained into adulthood through interactions with a fibroblast population in skin fascia that we refer to as T_H2-interacting fascial fibroblasts (TIFFs), which expand in response to T_H2 cytokines to form subcutaneous fibrous bands. Activation of the T_H2-TIFF niche due to neonatal inflammation primes the skin for altered reparative responses to wounding. Furthermore, we identify fibroblasts in healthy human skin that express the TIFF transcriptional signature and detect these cells at high levels in eosinophilic fasciitis, an orphan disease characterized by inflammation and fibrosis of the skin fascia. Taken together, these data define a previously unidentified T_H2 cell niche in skin and functionally characterize a disease-associated fibroblast population. The results also suggest a mechanism of immunological priming whereby inflammation early in life creates networks between adaptive immune cells and stromal cells to establish an immunological set-point in tissues that is maintained throughout life.

Primary Cilia Are Preserved in Cellular Blue and Atypical Blue Nevi and Lost in Blue Nevus-like Melanoma

Distinguishing cellular blue nevi (CBNs) and atypical CBNs from blue nevus-like melanoma (BNLM) can be diagnostically challenging. Immunohistochemistry may inform the diagnosis in a subset of cases but is not always diagnostic. Further, ancillary molecular testing is expensive and often requires significant tissue to complete. Primary cilia are cell-surface organelles with roles in signal transduction pathways and have been shown to be preserved in conventional melanocytic nevi but lost in melanoma. Immunofluorescence staining of primary cilia can be performed using a single standard-thickness formalin-fixed paraffin-embedded tissue section and has a turnaround time similar to immunohistochemistry. The percentage of tumoral melanocytes retaining a primary cilium is quantified and reported as the ciliation index. In the current study, we explored the utility of the ciliation index in a series of 31 blue nevus-like lesions, including CBNs (12), atypical CBNs (15), and BNLM (4). The average ciliation index for the CBNs was 59±18%, with a median of 60 (range: 28 to 87). The average ciliation index for atypical CBNs was 59±23, with a median of 59 (range: 20 to 93). The average ciliation index for BNLM was 4±3, with a median of 3 (range: 1 to 8). There was no significant difference in ciliation index between the CBN and atypical CBN categories. There was a significant difference between CBN and BNLM and between atypical CBNs and BNLM (P<0.001 for each). Here, we show that ciliation index is a quantitative diagnostic tool useful in the setting of blue nevus-like neoplasms, with benefits including cost and time efficiency.

Association of a Proposed New Staging System for Folliculotropic Mycosis Fungoides With Prognostic Variables in a US Cohort

Importance

A new cutaneous staging system for folliculotropic mycosis fungoides (FMF) has been purported to better estimate survival compared with the staging system for conventional mycosis fungoides.

Objective

To analyze predictive variables associated with survival and evaluate the effectiveness of the newly proposed staging system for estimating overall survival and disease-specific survival (DSS) in a US cohort.

Design, Setting, and Participants

This cohort study assessed 195 patients with FMF in the dermatopathology database of the University of California, San Francisco from January 1, 1990, to April 31, 2012, for eligibility. A total of 153 patients were excluded for the following reasons: (1) alternative diagnoses were favored ranging from benign dermatitides to other forms of cutaneous lymphoma; (2) technical problems with slides; and (3) lack of follow-up information. Data were analyzed from January 1, 2018, to August 31, 2020.

Main Outcomes and Measures

Kaplan-Meier curves were used to estimate overall survival and DSS for the entire cohort. Possible predictive variables associated with survival were evaluated using Cox proportional hazards regression modeling. Each variable was examined separately, followed by a multiple-variable model. Kaplan-Meier curves were used to estimate overall survival and DSS by subdividing the cohort into early- and advanced-stage cutaneous disease.

Results

Forty-two patients were included in the analysis (mean age at diagnosis, 55 [range, 8-89] years; 31 men [74%]). For the entire cohort, the estimated 5-year overall survival rate was 89% (95% CI, 79%-99%); 10-year rate, 78% (95% CI, 63%-92%); and 15-year rate, 58% (95% CI, 31%-85%). Estimated 5- and 10-year DSS rates were 89% (95% CI, 79%-99%); 15-year rate, 80% (95% CI, 61%-99%). For overall survival in the multiple-variable Cox proportional hazards regression model, only age was statistically significant (hazard ratio [HR] per 10-year age increase, 3.1; 95% CI, 1.4-7.2; P = .008), whereas for DSS, only cutaneous disease was statistically significant (HR, 11.4; 95% CI, 1.3-103.0; P = .03). When stage stratified, the 5-year estimated overall survival rate for early-stage disease was 96% (95% CI, 89%-103%); 10-year rate, 82% (95% CI, 65%-98%); and 15-year rate, 65% (95% CI, 33%-97%). For advanced-stage disease, the estimated 5- and 10-year overall survival rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%). For early-stage cutaneous disease, the estimated 5-, 10- and 15-year DSS rates were all 96% (95% CI, 89%-103%). For advanced-stage cutaneous disease, the estimated 5- and 10-year DSS rates were 70% (95% CI, 41%-98%); the 15-year rate, 53% (95% CI, 16%-89%).

Conclusions and Relevance

Cox proportional hazards regression modeling demonstrated cutaneous stage to be the only statistically significant predictive variable associated with DSS. Subdividing FMF into early and advanced cutaneous stages was associated with effective estimation of survival in this cohort. Thus, findings suggest that FMF is a heterogeneous disease with early and advanced cutaneous stages; that the new staging system is effective in estimating survival in a US cohort; and that the poor prognosis initially associated with FMF only applies to the advanced cutaneous stage.

BAP1-inactivated melanocytic tumors show prominent centrosome amplification and associated loss of primary cilia

BACKGROUND

BRCA1-associated protein (BAP1) is a tumor suppressor whose loss is associated with various malignancies. The primary cilium is an organelle involved in signal transduction and cell cycle progression. Primary cilia have been shown to be absent in melanoma but retained to some extent in melanocytic nevi, and the severity of dysplasia influences the degree of cilia loss. Additionally, studies have revealed roles for BAP1 in centrosome and mitotic spindle formation. Because the primary cilium is nucleated on the mother centriole, we examined the connection between the presence of primary cilia and the formation of centrosomes in BAP1-inactivated melanocytic tumors (BIMTs).

METHODS

We evaluated the cilia and centrosomes in 11 BIMTs and five conventional melanocytic nevi using immunofluorescence staining of acetylated alpha-tubulin and gamma-tubulin.

RESULTS

We found that, compared to nevi, BIMTs show loss of primary cilia and amplification of centrosomes. Occasional nevi also showed increased centrioles; however, these foci of amplification were more likely to be ciliated than those in BIMTs.

CONCLUSIONS

Although centrosome amplification does not absolutely correlate with loss of primary cilia in melanocytic neoplasms, absence of BAP1 exacerbates the phenotype. Moreover, aberrant centrosome and cilia formation are likely critical in the pathogenesis of other BAP1-inactivated tumors.

Fusion partners of NTRK3 affect subcellular localization of the fusion kinase and cytomorphology of melanocytes

A subset of Spitz tumors harbor fusions of NTRK3 with ETV6, MYO5A, and MYH9. We evaluated a series of 22 melanocytic tumors in which an NTRK3 fusion was identified as part of the diagnostic workup. Tumors in which NTRK3 was fused to ETV6 occurred in younger patients were predominantly composed of epithelioid melanocytes and were classified by their histopathologic features as Spitz tumors. In contrast, those in which NTRK3 was fused to MYO5A were predominantly composed of spindled melanocytes arrayed in fascicles with neuroid features such as pseudo-Verocay bodies. To further investigate the effects of the fusion kinases ETV6-NTRK3 and MYO5A-NTRK3 in melanocytes, we expressed them in immortalized melanocytes and determined their subcellular localization by immunofluorescence. ETV6-NTRK3 was localized to the nucleus and diffusely within the cytoplasm and caused melanocytes to adopt an epithelioid cytomorphology. In contrast, MYO5A-NTRK3, appeared excluded from the nucleus of melanocytes, was localized to dendrites, and resulted in a highly dendritic cytomorphology. Our findings indicate that ETV6-NTRK3 and MYO5A-NTRK3 have distinct subcellular localizations and effects on cellular morphology.

Multiple desmoplastic Spitz nevi with BRAF fusions in a patient with ring chromosome 7 syndrome

Patients with non-supernumerary ring chromosome 7 syndrome have an increased incidence of hemangiomas, café-au-lait spots, and melanocytic nevi. The mechanism for the increased incidence of these benign neoplasms is unknown. We present the case of a 22-year-old man with ring chromosome 7 and multiple melanocytic nevi. Two nevi, one on the right ear and the other on the right knee, were biopsied and diagnosed as desmoplastic Spitz nevi. Upon targeted next-generation DNA sequencing, both harbored BRAF fusions. Copy number alterations and fluorescence in situ hybridization (FISH) for BRAF suggested that the fusions arose on the ring chromosome 7. Hence, one reason for increased numbers of nevi in patients with non-supernumerary ring chromosome 7 syndrome may be increased likelihood of BRAF fusions, due to the instability of the ring chromosome.

Expanding the Spectrum of Microscopic and Cytogenetic Findings Associated With Spitz Tumors With 11p Gains

A subset of Spitz tumors is associated with a copy number increase of chromosome 11p and activating mutations of HRAS. These aberrations have been reported to occur in association with desmoplastic Spitz nevi. Little is known to what extent 11p gains can also be found in nondesmoplastic tumors. To learn more about the spectrum of microscopic and cytogenetic changes that can be seen in Spitz lesions in association with 11p gains, we reviewed the clinical and pathologic features of 40 cases. Patient ages ranged from 3 to 75 years. The most common anatomic site was the head and neck region, followed by the upper extremities. Prominent desmoplasia was present in 10 cases. Seven tumors lacked significant stromal fibrosis. Twenty tumors were mitotically active. Novel microscopic features encountered in a few cases include a tumor with a polypoid silhouette and papillomatous surface and rare atypical tumors with a deep bulbous growth pattern. Among 36 cases analyzed by single-nucleotide polymorphism array or comparative genomic hybridization, 28 tumors had gains of the entire or near-entire p-arm of chromosome 11 with no other coexisting unbalanced genomic aberration. Eight cases had additional changes; 6 of these with 1 additional aberration per case, and 2 cases had several chromosomal aberrations. We also examined a subset of tumors by fluorescence in situ hybridization for the HRAS gene locus (11p15.5). All tumors were fluorescence in situ hybridization-positive. In conclusion, we expand the spectrum of pathologic findings associated with Spitz tumors with 11p gains. This cytogenetic aberration is not restricted to desmoplastic Spitz nevi. It can also be seen in nondesmoplastic and papillomatous lesions and atypical melanocytic tumors with a deep bulbous growth. We also document that in some Spitz tumors additional cytogenetic aberrations may be found, the significance of which remains to be determined.

Folliculotropic mycosis fungoides driven by DOCK8 immunodeficiency syndrome

DOCK8 immunodeficiency syndrome (DIDS) represents a rare primary immunodeficiency associated with cutaneous viral infections, allergy, and increased risk of malignancy. We report a case of folliculotropic mycosis fungoides with spontaneous resolution occurring in a patient with DIDS.

Idiopathic pure sudomotor failure: A review and two cases

Idiopathic pure sudomotor failure (IPSF) is a rare disease characterized by acquired impairment in total body sweating despite exposure to heat or exercise. Its etiology is unknown but thought to involve defective cholinergic receptors on eccrine sweat glands. This article reviews the epidemiology, pathophysiology, presentation, and management of IPSF. Additionally, we report two cases of IPSF treated with multimodal therapy, including stacked antihistamine regimens and omalizumab, resulting in symptom improvement. This is the first report of treatment of IPSF with omalizumab, although its benefit is uncertain and requires further study.

Ciliation Index Is a Useful Diagnostic Tool in Challenging Spitzoid Melanocytic Neoplasms

The loss of primary cilia on melanocytes is a useful biomarker for the distinction of melanoma from conventional melanocytic nevi. It is unknown whether ciliation status is beneficial for diagnosing spitzoid tumors-a subclass of melanomas that present inherently ambiguous histology and are challenging to classify. We evaluated the Ciliation Index (CI) in 68 cases of spitzoid tumors ranging from Spitz nevi and atypical Spitz tumors to spitzoid melanoma. We found a significant decrease in CI within the spitzoid melanoma group when compared with either the Spitz nevi or atypical Spitz tumors groups. In addition, we used a machine-learning-based algorithm to determine the value of CI when considered in combination with other histopathologic and molecular features commonly used for diagnosis. We found that a low CI was consistently ranked as a top predictive feature in the diagnosis of malignancy. Predictive models trained on only the top four predictive features (CI, asymmetry, hyperchromatism, and cytologic atypia) outperformed standard histologic assessment in an independent validation cohort of 56 additional cases. The results provide an alternative approach to evaluate diagnostically challenging melanocytic lesions, and further support the use of CI as an ancillary diagnostic test.

Spitz melanoma is a distinct subset of spitzoid melanoma

Melanomas that have histopathologic features that overlap with those of Spitz nevus are referred to as spitzoid melanomas. However, the diagnostic concept is used inconsistently and genomic analyses suggest it is a heterogeneous category. Spitz tumors, the spectrum of melanocytic neoplasms extending from Spitz nevi to their malignant counterpart Spitz melanoma, are defined in the 2018 WHO classification of skin tumors by the presence of specific genetic alterations, such as kinase fusions or HRAS mutations. It is unclear what fraction of "spitzoid melanomas" defined solely by their histopathologic features belong to the category of Spitz melanoma or to other melanoma subtypes. We assembled a cohort of 25 spitzoid melanomas diagnosed at a single institution over an 8-year period and performed high-coverage DNA sequencing of 480 cancer related genes. Transcriptome wide RNA sequencing was performed for select cases. Only nine cases (36%) had genetic alterations characteristic of Spitz melanoma, including HRAS mutation or fusion involving BRAF, ALK, NTRK1, or MAP3K8. The remaining cases were divided into those with an MAPK activating mutation and those without an MAPK activating mutation. Both Spitz melanoma and spitzoid melanomas in which an MAPK-activating mutation could not be identified tended to occur in younger patients on skin with little solar elastosis, infrequently harbored TERT promoter mutations, and had a lower burden of pathogenic mutations than spitzoid melanomas with non-Spitz MAPK-activating mutations. The MAPK-activating mutations identified affected non-V600 residues of BRAF as well as NRAS, MAP2K1/2, NF1, and KIT, while BRAF V600 mutations, the most common mutations in melanomas of the WHO low-CSD category, were entirely absent. While the "spitzoid melanomas" comprising our cohort were enriched for bona fide Spitz melanomas, the majority of melanomas fell outside of the genetically defined category of Spitz melanomas, indicating that histomorphology is an unreliable predictor of Spitz lineage.

Clustered cases of acral perniosis: Clinical features, histopathology, and relationship to COVID-19

BACKGROUND/OBJECTIVES

A recent marked increase in pediatric and adult patients presenting with purpuric acral lesions concerning for ischemia, thrombosis and necrosis has been observed in COVID-19 prevalent regions worldwide. The clinical and histopathological features and relationship to COVID-19 have not been well described. The objective of this case series is to describe the clinical features and determine the histopathologic findings and clinical implications of the clusters of acral perniosis cases identified in pediatric patients.

METHODS

We describe six otherwise healthy adolescents-three siblings per family from two unrelated families-presented within a 48-hour period in April, 2020, with acral perniosis-like lesions in the context of over 30 similar patients who were evaluated within the same week.

RESULTS

Affected patients had mild symptoms of viral upper respiratory infection (URI) or contact with symptomatic persons 1-2 weeks preceding the rash. They all presented with red to violaceous macules and dusky, purpuric plaques scattered on the mid and distal aspects of the toes. Skin biopsies performed on each of the six patients demonstrated near identical histopathologic findings to those of idiopathic perniosis, with a lymphocytic inflammatory infiltrate without evidence of thromboembolism or immune complex vasculitis. While SARS-CoV-2 polymerase chain reaction was negative, testing was performed 1-2 weeks after URI symptoms or sick contact exposure.

CONCLUSION

We offer a clinical approach to evaluation of patients with this presentation and discuss the possibility that these skin findings represent a convalescent-phase cutaneous reaction to SARS-CoV-2 infection.

Melanocytic tumors with MAP3K8 fusions: report of 33 cases with morphological-genetic correlations

We report a series of 33 skin tumors harboring a gene fusion of the MAP3K8 gene, which encodes a serine/threonine kinase. The MAP3K8 fusions were identified by RNA sequencing in 28 cases and by break-apart FISH in five cases. Cases in which fusion genes were fully characterized demonstrated a fusion of the 5' part of MAP3K8 comprising exons 1-8 in frame to one of several partner genes at the 3' end. The fusion genes invariably encoded the intact kinase domain of MAP3K8, but not the inhibitory domain at the C-terminus. In 13 (46%) of the sequenced cases, the 3' fusion partner was SVIL. Other recurrent 3' partners were DIP2C and UBL3, with additional fusion partners that occurred only in a single tumor. Clinically, the lesions appeared mainly in young adults (2-59 years of age; median = 18), most commonly involving the lower limbs (55%). Five cases were diagnosed as Spitz nevus, 13 as atypical Spitz tumor, and 15 as malignant Spitz tumor. Atypical and malignant cases more commonly occurred in younger patients. Atypical Spitz tumors and malignant Spitz tumors cases tended to show epidermal ulceration (32%), a dermal component with giant multinucleated cells (32%), and clusters of pigmented cells in the dermis (32%). Moreover, in atypical and malignant cases, a frequent inactivation of CDKN2A (21/26; 77%) was identified either by p16 immunohistochemistry, FISH, or comparative genomic hybridization. Gene expression analysis revealed that MAP3K8 expression levels were significantly elevated compared to a control group of 57 Spitz lesions harboring other known kinase fusions. Clinical follow-up revealed regional nodal involvement in two of six cases, in which sentinel lymph node biopsy was performed but no distant metastatic disease after a median follow-up time of 6 months.

Concurrent presentation of brain arteriovenous malformation, peripheral arteriovenous malformation, and cerebellar astrocytoma: Case report

Background:

We report a rare case of a 19-year-old female progressively affected by a peripheral arteriovenous malformation (pAVM), a midline cerebellar astrocytoma, and a brain arteriovenous malformation (bAVM).

Case description:

She presented with a pulsatile mass on her left cheek, which was classified as a pAVM through angiography. Following treatment with embolization and surgical resection, she returned with enlargement of the mass and imaging incidentally identified a cerebellar astrocytoma. Suboccipital craniotomy, C1 laminectomy, and endoscopic third ventriculostomy were subsequently performed. She was later treated again for growth of her pAVM, and angiography revealed the presence of a left temporal bAVM, which was resected via a pterional craniotomy.

Conclusions:

Pathological staining identified activation of mTOR and RAS/MAPK pathway in the patient’s pAVM and bAVM tissue samples. Furthermore, genetic sequencing demonstrated an activating MAPK21 (K57N) mutation in the pAVM and a gain of distal chromosome 7q in the pilocytic astrocytoma. No germline mutation was identified to explain all pathologies. This case demonstrates the need for continued development and further integration of multi-disciplinary genetic, radiological, and neurological treatment teams to effectively care for such complex presentations.

Use of the Ciliation Index to Distinguish Invasive Melanoma From Associated Conventional Melanocytic Nevi

Our understanding of melanoma precursors and progression to melanoma has developed as a result of advances in the field of molecular diagnostics. We now better understand the potential for genetic heterogeneity within a single lesion. Combined tumors can pose a diagnostic challenge when deciding the line between benign and malignant, which in turn has direct implications for patient management. Primary cilia (PC) are ubiquitous sensory organelles that have essential functions in cellular proliferation, differentiation, and development. The ciliation index (percentage of ciliated melanocytes) has been shown to reliably differentiate melanoma, which fail to ciliate, from melanocytic nevi, which retain PC. We therefore analyzed the potential for using the ciliation index to differentiate benign and malignant components in combined melanocytic lesions. We collected patient samples (n = 10) of unequivocal combined lesions with both melanoma and associated nevus components. Melanocytes were highlighted with SOX10 and costained with gamma-Tubulin and acetylated alpha-Tubulin to highlight the basal body and cilium, respectively. The number of melanocytes retaining cilia under high-power microscopy was examined. The melanoma component had average of 4% ciliation (SD: 7%), whereas the associated nevus component was significantly higher with 59% ciliation (SD: 17%). These data show that PC may be a reliable means of distinguishing benign from malignant components within a single tumor. The ciliation index may be a helpful tool in distinguishing challenging cases of combined lesions of melanoma in situ with a dermal nevus component from invasive melanoma, thus promoting improved staging and clinical management.

Maximizing the clinical utility of descriptive lymphoid pathology reporting

Dermatopathology reporting can be both exact and inexact. Exact reporting represents the use of terminology that corresponds to a disease sui generis, such as discoid lupus erythematosus or disseminated superficial porokeratosis. Inexact reporting can vary greatly amongst various practitioners-both in terms of the exact semantics used and also stylistically-and can be used habitually by pathologists as a means to provide cover for diagnostic uncertainty or inexperience. This article explores the use of descriptive (inexact) reporting as it applies to cutaneous lymphoma and its differential diagnosis. A collection of practical descriptive diagnostic categories that will be of use to both dermatologists and dermatopathologists is included.

Clinical Features of Neutrophilic Dermatosis Variants Resembling Necrotizing Fasciitis

Importance

Pyoderma gangrenosum and necrotizing Sweet syndrome are diagnostically challenging variants of neutrophilic dermatosis that can clinically mimic the cutaneous and systemic features of necrotizing fasciitis. Improved characterization of these rare variants is needed, as improper diagnosis may lead to inappropriate or delayed treatment and the potential for morbidity.

Objective

To determine the characteristics of necrotizing neutrophilic dermatosis to improve diagnostic accuracy and distinguish from infection.

Design, Setting, and Participants

A case series of patients with necrotizing neutrophilic dermatosis treated at 3 academic hospitals (University of California San Francisco, Oregon Health and Science University, and University of Minnesota) from January 1, 2015, to December 31, 2017, was performed along with a literature review of related articles published between January 1, 1980, and December 31, 2017. Data were obtained from medical records as well as Medline and Embase databases. All patients had signs resembling necrotizing infection and had a final diagnosis of pyoderma gangrenosum with systemic features or necrotizing Sweet syndrome. Patients were excluded if a diagnosis other than neutrophilic dermatosis was made, if key clinical information was missing, and if reported in a non-English language.

Main Outcomes and Measures

Description of key characteristics of necrotizing neutrophilic dermatosis.

Results

Overall, 54 patients with necrotizing neutrophilic dermatosis were included, of which 40 had pyoderma gangrenosum with systemic features and 14 had necrotizing Sweet syndrome. Of the 54 patients, 29 (54%) were male and 25 (46%) were female, with a mean (SD) age of 51 (19) years. Skin lesions commonly occurred on the lower (19 [35%]) and upper (13 [24%]) extremities and developed after a surgical procedure (22 [41%]) or skin trauma (10 [19%]). Shock was reported in 14 patients (26%), and leukemoid reaction was seen in 15 patients (28%). Of the patients with necrotizing neutrophilic dermatosis, 51 (94%) were initially misdiagnosed as necrotizing fasciitis and subsequently received inappropriate treatment. Debridement was performed in 42 patients (78%), with a mean (SD) of 2 (2 [range, 1-12]) debridements per patient. Four amputations (7%) were performed. Forty-nine patients (91%) received antibiotics when necrotizing neutrophilic dermatosis was misdiagnosed as an infection, and 50 patients (93%) received systemic corticosteroids; all patients responded to immunosuppressants.

Conclusions and Relevance

A complex spectrum of clinical findings of pyoderma gangrenosum and Sweet syndrome with prominent systemic inflammation exists that defines a new subset of neutrophilic dermatoses, termed necrotizing neutrophilic dermatoses; recognizing the difference between this variant and severe infection may prevent unnecessary surgical procedures and prolonged disease morbidity associated with a misdiagnosis and may expedite appropriate medical management.

Cutaneous Non-Neural Granular Cell Tumors Harbor Recurrent ALK Gene Fusions

Non-neural granular cell tumor (NNGCT; also known as primitive polypoid granular cell tumor) is a rare neoplasm composed of large ovoid cells with abundant granular cytoplasm, variable nuclear pleomorphism, and the potential for regional lymph node spread. In contrast to conventional granular cell tumor (GCT), NNGCT lacks S100 expression and can exhibit greater nuclear atypia and mitotic activity. Therefore, we investigated clinicopathologic features of 12 NNGCT, and also used next-generation sequencing to identify potential driver events in a subset of NNGCT and 6 GCT. NNGCT demonstrated mild-to-moderate nuclear pleomorphism, variable mitotic activity (0 to 10/10 high-power fields), and were S100. Genetic analysis of 5 cutaneous NNGCT revealed gene fusions involving the anaplastic lymphoma kinase gene (ALK) in 3 cases (60%). Specifically, an interstitial deletion of chromosome 2 resulting in an in-frame fusion of dyanactin 1 (DCTN1) to ALK was identified in 2 cases, and a translocation resulting in a fusion between sequestosome 1 (SQSTM1) on chromosome 5 and ALK was identified in one case. Two of 6 GCT (33%) showed gains of chromosome 7. No other molecular or chromosomal alterations were detected in NNGCT and GCT. ALK immunohistochemistry revealed weak-to-moderate positivity in 4/9 cutaneous NNCGT (44%) including all 3 tumors with ALK fusions. Three oral NNGCT lacked ALK expression. NNGCT with ALK immunostaining did not have morphologic features distinguishing them from those without ALK staining. Our results demonstrate that a subset of NNGCT harbor ALK fusions, suggest that NNGCT are molecularly diverse, and further substantiate NNGCT as distinct from GCT.

Cutaneous endometriosis

Cutaneous endometriosis is a disorder that primarily affects women of reproductive age. The disorder is most commonly associated with cyclical pain during menses, but it can be difficult to diagnose in the absence of these symptoms and requires biopsy testing for a definitive diagnosis. We report on a case of a 41-year-old patient undergoing hormonal therapy for infertility who presented with a painful firm subcutaneous nodule in the umbilicus. She was ultimately diagnosed with cutaneous endometriosis and underwent surgical excision. In this report, we discuss the differential diagnosis and comment on treatment options, including surgical excision with wide margins or treatment with hormonal agents, such as danazol or leuprolide. Finally, we discuss whether patients with cutaneous endometriosis should receive an additional evaluation for pelvic endometriosis.

Ki-67 and p16 Immunostaining Differentiates Pagetoid Bowen Disease From "Microclonal" Seborrheic Keratosis

OBJECTIVES

We observed keratoses with "clonal" nests present as numerous tiny collections, in which cells in "pagetoid" array are found, a configuration we termed microclonal seborrheic keratosis (MSK). To better distinguish MSK from pagetoid Bowen disease (PBD), we investigated use of immunohistochemical staining.

METHODS

Biopsy specimens of 26 MSKs, 17 PBDs, and 11 borderline cases were reviewed for histopathology and stained with p53, Ki-67, and p16.

RESULTS

High expression of Ki-67 and p16 was observed in 12 (80%) of 15 PBDs and in one (4%) of 23 MSKs. Low expression of p16 and high expression of Ki-67 were observed in 16 (70%) of 23 MSKs and in two (13%) of 15 PBDs. Expression of p16 was elevated in 12 (80%) of 15 PBDs and in three (13%) of 23 MSKs (P < .0001).

CONCLUSIONS

We describe a "microclonal" variant of seborrheic keratosis with morphology sometimes challenging to distinguish from PBD. High expression of p16 and Ki-67 or p16 alone favors the diagnosis of PBD over MSK.

Combined activation of MAP kinase pathway and β-catenin signaling cause deep penetrating nevi

Deep penetrating nevus (DPN) is characterized by enlarged, pigmented melanocytes that extend through the dermis. DPN can be difficult to distinguish from melanoma but rarely displays aggressive biological behavior. Here, we identify a combination of mutations of the β-catenin and mitogen-activated protein kinase pathways as characteristic of DPN. Mutations of the β-catenin pathway change the phenotype of a common nevus with BRAF mutation into that of DPN, with increased pigmentation, cell volume and nuclear cyclin D1 levels. Our results suggest that constitutive β-catenin pathway activation promotes tumorigenesis by overriding dependencies on the microenvironment that constrain proliferation of common nevi. In melanoma that arose from DPN we find additional oncogenic alterations. We identify DPN as an intermediate stage in the step-wise progression from nevus to melanoma. In summary, we delineate specific genetic alterations and their sequential order, information that can assist in the diagnostic classification and grading of these distinctive neoplasms.

Deep penetrating nevi (DPN) are unusual melanocytic neoplasms with unknown genetic drivers. Here the authors show that majority of DPN harbor activating mutations in the β-catenin and the MAP-kinase pathways; this characteristic can help in the classification and grading of these distinctive neoplasms.

Loss of retinoblastoma in pleomorphic fibroma: An immunohistochemical and genomic analysis

BACKGROUND

Pleomorphic fibroma is a curious neoplasm that exhibits striking cytologic atypia, yet behaves in benign fashion. The cytologic features include single cells with pleomorphic nuclei and scattered giant cells resembling the neoplastic cells of pleomorphic lipoma, a tumor with known retinoblastoma (Rb) loss.

METHODS

We assessed the demographic and histopathologic features of a cohort of 26 pleomorphic fibromas, including assessment with immunostaining for Rb, p16 and Ki-67. Array comparative genomic hybridization (aCGH) was used to assess a limited number of tumors for genomic aberrations.

RESULTS

Of the 26 pleomorphic fibromas analyzed, 19 occurred in women and 7 in men, with a mean age of 47 years. The anatomic locations were variable. Immunostaining showed loss of Rb protein expression in all cases and diffuse p16 expression in 85%. Ki-67 labeling rate was below 10% in 85%. Chromosome 13q loss was found in 7 of 7 pleomorphic fibromas assessed with aCGH. Recurrent loss of 17p, 16q and 10q were also found.

CONCLUSION

We report recurrent loss of RB1 on chromosome 13q in pleomorphic fibromas, confirmed by both protein expression loss and loss of 13q by aCGH. This result indicates pleomorphic fibroma shares the same genetic abnormalities as spindle cell and pleomorphic lipomas.

Eosinophilic Pustular Folliculitis in Children after Stem Cell Transplantation: An Eruption Distinct from Graft-Versus-Host Disease

Eosinophilic pustular folliculitis (EPF) is a rare cutaneous disorder that typically occurs in three clinical contexts: men, individuals who are immunosuppressed or have human immunodeficiency virus, and infants. A fourth subtype occurring 2 to 3 months after hematopoietic stem cell transplantation (HSCT) has recently been described in several adults. We report two cases of EPF arising in children after HSCT. It is important to recognize this form of EPF after HSCT and differentiate it from graft-versus-host disease since it responds readily to topical steroids and appears to have an excellent prognosis.

NTRK3 kinase fusions in Spitz tumours

Oncogenic fusions in TRK family receptor tyrosine kinases have been identified in several cancers and can serve as therapeutic targets. We identified ETV6-NTRK3, MYO5A-NTRK3 and MYH9-NTRK3 fusions in Spitz tumours, and demonstrated that NTRK3 fusions constitutively activate the mitogen-activated protein kinase, phosphoinositide 3-kinase and phospholipase Cγ1 pathways in melanocytes. This signalling was inhibited by DS-6051a, a small-molecule inhibitor of NTRK1/2/3 and ROS1. NTRK3 fusions expand the range of oncogenic kinase fusions in melanocytic neoplasms and offer targets for a small subset of melanomas for which no targeted options currently exist. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Multiple Hereditary Infundibulocystic Basal Cell Carcinoma Syndrome Associated With a Germline SUFU Mutation

IMPORTANCE

Multiple hereditary infundibulocystic basal cell carcinoma syndrome (MHIBCC) is a rare genodermatosis in which numerous indolent, well-differentiated basal cell carcinomas develop primarily on the face and genitals, without other features characteristic of basal cell nevus syndrome. The cause is unknown. The purpose of the study was to identify a genetic basis for the syndrome and a mechanism by which the associated tumors develop.

OBSERVATIONS

Whole-exome sequencing of 5 tumors and a normal buccal mucosal sample from a patient with MHIBCC was performed. A conserved splice-site mutation in 1 copy of the suppressor of fused gene (SUFU) was identified in all tumor and normal tissue samples. Additional distinct deletions of the trans SUFU allele were identified in all tumor samples, none of which were present in the normal sample.

CONCLUSIONS AND RELEVANCE

A germline SUFU mutation was present in a patient with MHIBCC, and additional acquired SUFU mutations underlie the development of infundibulocystic basal cell carcinomas. The downstream location of the SUFU gene within the sonic hedgehog pathway may explain why its loss is associated with relatively well-differentiated tumors and suggests that MHIBCC will not respond to therapeutic strategies, such as smoothened inhibitors, that target upstream components of this pathway.

Neutrophil-rich subcutaneous fat necrosis of the newborn: A potential mimic of infection

BACKGROUND

The inflammatory infiltrate seen in biopsy specimens obtained from patients with subcutaneous fat necrosis of the newborn (SCFN) has classically been described as consisting mostly of histiocytes. However, we encountered patients with SCFN whose biopsy specimens revealed mostly neutrophils, prompting infection to be an initial consideration.

OBJECTIVES

We sought to describe cases of SCFN in which neutrophils formed the majority of the infiltrate at our institution and in the literature.

METHODS

We performed a retrospective analysis of patients with SCFN reported at our institution and a literature review of SCFN.

RESULTS

Thirteen cases of SCFN were identified at our institution. In 2 of 13 cases, neutrophils composed >75% of the inflammatory infiltrate, and both lesions were 1 day old. From the literature review, neutrophils were mentioned as a component of the infiltrate in 10 of 124 cases, but in none were neutrophils described as forming the majority of the infiltrate.

LIMITATIONS

This study is limited by its retrospective nature and small sample size.

CONCLUSIONS

Neutrophils can comprise most of the inflammatory cells in patients with SCFN, especially early in the course of the disease. This variant of SCFN can be easily mistaken for infection.

The distribution of cutaneous metastases correlates with local immunologic milieu

BACKGROUND

Metastases to the skin are found with increased frequency at certain sites, such as the scalp, but the biological factors that influence this distribution are not understood.

OBJECTIVE

We aimed to compare the proportional frequency of metastases at various cutaneous locations with the immunologic microenvironments at those sites.

METHODS

We retrospectively identified all biopsy specimens of cutaneous metastases diagnosed at our institution from 1991 to 2014 (n = 1984) and mapped their anatomic distribution while controlling for regional surface area. Using a separate, mapped cohort of normal-appearing skin samples (n = 140), we measured the density of regulatory T cells, CD4(+) effector T cells, and CD8(+) T cells by flow cytometry.

RESULTS

Per unit surface area, cutaneous metastases arise most commonly on the head and neck, followed by the trunk, upper extremities, and lower extremities, respectively. Sites with more frequent metastases tend to contain a greater density of regulatory T cells and a lower proportion of CD8(+) T cells (P < .05).

LIMITATIONS

Immunologic factors were only assessed in control tissue and were not measured from patients with metastatic disease in this correlative single-center study.

CONCLUSION

The distribution of cutaneous metastases follows the distribution of regulatory and effector T cells in skin. Further studies are required to prove a mechanistic association between local immunologic factors and the development of cutaneous metastases.

Herpes zoster granulomatous dermatitis: histopathologic findings in a case series

Several types of cutaneous reactions have been reported to arise at the site of herpes zoster (HZ) infection weeks to years after the acute disease. Among these, granulomatous reactions are the most frequently reported. In this study, we describe the spectrum of histopathologic findings of HZ granulomatous reactions observed in 26 patients with cutaneous lesions confined to the area of previous HZ eruption and compare them with biopsy specimens taken from 25 patients with acute HZ. All patients with persistent reactions from whom history was available presented within 12 weeks of the onset of the acute eruption. The most frequent findings were interstitial granulomatous dermatitis with lymphocytes, histiocytes and multinucleated giant cells displaying elastophagocytosis and a perineural, perivascular and perieccrine mononuclear inflammatory infiltrate rich in lymphocytes and plasma cells. Less common features included intra-arrector and peri-arrector pili granulomas, follicular dilatation and hyperkeratosis, and vasculitis. Specimens from patients with acute HZ were found to have small numbers of perineural plasma cells and most had subtle granulomatous inflammation, in patterns similar to the group with late granulomatous reactions. Our findings suggest that granulomatous reactions to varicella zoster virus represent a persistent evolving inflammatory reaction after acute infection.

Updates in adult-onset Still disease: Atypical cutaneous manifestations and associations with delayed malignancy

Adult-onset Still disease (AOSD) is a systemic inflammatory disorder that is clinically characterized by a heterogeneous constellation of symptoms and signs. Though an evanescent eruption is the classic cutaneous finding, recent literature has highlighted atypical rashes associated with Still disease. A second emerging concept in presentations of AOSD is its association with malignancy. This review focuses on these concepts: the clinical spectrum of atypical skin manifestations and AOSD as a paraneoplastic phenomenon. PubMed-MEDLINE was screened for peer-reviewed articles describing atypical presentations of AOSD and cases associated with malignancy. Erythematous, brown or violaceous, persistent papules and plaques were the most common cutaneous finding (28/30 [93%]). Linear configurations were also rarely described. Of these patients, 81% concurrently had the typical evanescent skin eruption. There were 31 patients with associated malignancies, most commonly breast cancer and lymphoma. The diagnosis of malignancy did not precede or immediately follow a clinical presentation otherwise consistent with AOSD in a considerable subset of patients (42%). Understanding the cutaneous spectrum of AOSD and heightened awareness for its delayed association with malignancy may lead to improved recognition of cutaneous variants and reinforce the need for diagnostic evaluation and long-term follow-up for malignancy in patients with this clinical presentation.

Factors associated with pruritic papular eruption of human immunodeficiency virus infection in the antiretroviral therapy era

BACKGROUND

Pruritic papular eruption (PPE) of HIV is common in HIV-infected populations living in the tropics. Its aetiology has been attributed to insect bite reactions and it is reported to improve with antiretroviral therapy (ART). Its presence after at least 6 months of ART has been proposed as one of several markers of treatment failure.

OBJECTIVES

To determine factors associated with PPE in HIV-infected persons receiving ART.

METHODS

A case-control study nested within a 500-person cohort from a teaching hospital in Mbarara, Uganda. Forty-five cases and 90 controls were enrolled. Cases had received ART for ≥ 15 months and had an itchy papular rash for at least 1 month with microscopic correlation by skin biopsy. Each case was individually matched with two controls for age, sex and ART duration.

RESULTS

Twenty-five of 45 cases (56%) had microscopic findings consistent with PPE. At skin examination and biopsy (study enrolment), a similar proportion of PPE cases and matched controls had plasma HIV RNA < 400 copies mL(-1) (96% vs. 85%, P = 0·31). The odds of having PPE increased fourfold with every log increase in viral load at ART initiation (P = 0·02) but not at study enrolment. CD4 counts at ART initiation and study enrolment, and CD4 gains and CD8(+) T-cell activation measured 6 and 12 months after ART commencement were not associated with PPE. Study participants who reported daily insect bites had greater odds of being cases [odds ratio (OR) 8·3, P < 0·001] or PPE cases (OR 8·6, P = 0·01).

CONCLUSIONS

Pruritic papular eruption in HIV-infected persons receiving ART for ≥ 15 months was associated with greater HIV viraemia at ART commencement, independent of CD4 count. Skin biopsies are important to distinguish between PPE and other itchy papular eruptions.