Juvenile xanthogranuloma in Noonan syndrome.

Noonan syndrome (NS) is one of the common RASopathies. While the clinical phenotype in NS is variable, it is typically characterized by distinctive craniofacial features, cardiac defects, reduced growth, bleeding disorders, learning issues, and an increased risk of cancer. Several different genes cause NS, all of which are involved in the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway. Juvenile xanthogranuloma (JXG) is an uncommon, proliferative, self-limited cutaneous disorder that affects young individuals and may be overlooked or misdiagnosed due to its transient nature. A RASopathy that is known to be associated with JXG is neurofibromatosis type 1 (NF1). JXG in NF1 has also been reported in association with a juvenile myelomonocytic leukemia (JMML). As RASopathies, both NS and NF1 have an increased incidence of JMML. We report a 10-month-old female with NS who has a PTPN11 pathogenic variant resulting in a heterozygous SHP2 p.Y62D missense mutation. She was found to have numerous, small, yellow-pink smooth papules that were histopathologically confirmed to be JXG. In understanding the common underlying pathogenetic dysregulation of the Ras/MAPK pathway in both NS and NF1, this report suggests a possible molecular association for why NS individuals may be predisposed to JXG.

Ethical and professionalism issues in dermatopathology: A cross-sectional survey of American Society of Dermatopathology Members.

BACKGROUND: Data regarding ethical/professional issues affecting dermatopathologists are lacking despite their importance in establishing policy priorities and educational content for dermatopathology. METHODS: A 14-item cross-sectional survey about ethical/professional issues in dermatopathology was distributed over e-mail to members of the American Society of Dermatopathology from June to September 2019. RESULTS: Two hundred sixteen surveys were completed, with a response rate of 15.3%. Respondents ranked appropriate and fair utilization of healthcare resources (n = 83 or 38.6%) as the most often encountered ethical/professional issue. Conflict of interest was ranked as the most urgent or important ethical/professional issue (n = 83 or 39.3%). One hundred thirty-three (61.6%) respondents felt "somewhat" or "not at all" well equipped to handle ethical dilemmas in practice and 47 (22.8%) respondents identified a major or extreme burden (eg, have considered resigning/retiring) due to ethical challenges. CONCLUSIONS: Areas of priority in ethics and professionalism issues can guide future policy and educational content in dermatopathology.

An international survey about nail histology processing techniques.

BACKGROUND: There are limited data on nail histopathology techniques. The objective of this study was to examine nail histopathology techniques currently in use internationally. METHODS: An online survey was sent to the European Nail Society and Council for Nail Disorders during 2015-2016. RESULTS: There were 57 respondents, from twenty countries comprising dermatologists, podiatrists and pathologists. Specimens were unmarked or marked using ink or a suture and fixed in 10% formalin, from 6 to 48 hours before embedding in paraffin wax (90% [17/19]), liquid nitrogen (frozen section, 1/19) and 2-hydroxyethylmethacrylate (plastic, 1/19). Nail softening was undertaken by 71% (17/24) of respondents for 6 to 48 hours using Mollifex Gurr (12.5%, 3/24), 10% potassium hydroxide solution (12.5%, 3/24) or 10% potassium thioglycolate cream (12.5%, 3/24). Section thickness was 4 to 9 µm (62.5%), using a steel microtome (92%,12/13) on glass slides (91.6%, 11/12). Hematoxylin and eosin (H&E) was routine for all biopsies and Periodic acid Schiff (PAS) for fungus. The favored stain for differentiating melanin and hemoglobin was Fontana-Masson (60%, 6/10). For pigmented lesions, Melan-A was always employed by all respondents (9/9). CONCLUSION: Nail histopathology processing has some small variations from normal skin processing.

Generalized benign cutaneous reaction to cytarabine.

BACKGROUND: Cytarabine-induced toxicity manifests as various cutaneous morphologies. A generalized papular purpuric eruption has not been well described. OBJECTIVES: We aimed to characterize a distinct cytarabine-related eruption. METHODS: We reviewed all cases of cytarabine-related toxicity with papular purpuric eruptions or violaceous erythema at the University of California, San Francisco between 2006 and 2011. RESULTS: Sixteen cases were identified. The eruption began as erythematous papules that evolved into coalescing purpuric papules and plaques. It had affinity for intertriginous areas, neck, ears, and scalp. Pruritus was common, but no systemic complications were documented. Thirteen patients (81.3%) developed the eruption after completion of chemotherapy. Differential diagnosis often included viral exanthem (62.5%), drug eruption (50%), and vasculitis (37.5%). Histopathology was nonspecific but commonly demonstrated sparse lymphocytic infiltrates, spongiosis, and/or red cell extravasation. Importantly, the eruption was neither predicted by past cytarabine exposure nor predictive of future recurrence. LIMITATIONS: This is a review of cases from a single institution. Observation was limited to acute hospitalization, however, charts were reviewed for subsequent reactions on rechallenge. CONCLUSIONS: The eruption described herein represents a specific skin-limited reaction to cytarabine. Awareness of its characteristic morphology, distribution, and timeline will aid in clinical diagnosis. Reassurance concerning its benign nature will prevent unnecessary intervention or cessation of chemotherapy.

Atypical MRI features in soft-tissue arteriovenous malformation: a novel imaging appearance with radiologic-pathologic correlation.

BACKGROUND: The absence of a discrete mass, surrounding signal abnormality and solid enhancement are imaging features that have traditionally been used to differentiate soft-tissue arteriovenous malformations from vascular tumors on MRI. We have observed that these findings are not uncommon in arteriovenous malformations, which may lead to misdiagnosis or inappropriate treatment. OBJECTIVE: To estimate the frequency of atypical MRI features in soft-tissue arteriovenous malformations and assess their relationship to lesion size, location, tissue type involved and vascular architecture. MATERIALS AND METHODS: Medical records, MRI and histopathology were reviewed in consecutive patients with soft-tissue arteriovenous malformations in a multidisciplinary vascular anomalies clinic. Arteriovenous malformations were divided into those with and without atypical MRI findings (perilesional T2 signal abnormality, enhancement and/or a soft-tissue mass). Lesion location, size, tissue involved and vascular architecture were also compared between groups. Tissue stains were reviewed in available biopsy or resection specimens to assess relationships between MRI findings and histopathology. RESULTS: Thirty patients with treatment-naïve arteriovenous malformations were included. Fifteen lesions demonstrated atypical MRI. There was no difference in age, gender, lesion size or involved body part between the groups. However, more than half of the atypical lesions demonstrated multicompartmental involvement, and tiny intralesional flow voids were more common in atypical arteriovenous malformations. Histopathology also differed in atypical cases, showing densely packed endothelial cells with connective tissue architectural distortion and edema. CONCLUSION: Arteriovenous malformations may exhibit features of a vascular tumor on MRI, particularly when multicompartmental and/or containing tiny internal vessels. These features are important to consider in suspected fast-flow vascular malformations and may have implications with respect to their treatment.

Pigmented lesions of the nail unit.

Longitudinal melanonychia originates from pigmented and/or melanocytic lesions of the nail unit. It may be a less-common entity encountered in dermatologic practice, but it is often a vexing one. Lesions occurring at this location present particular problems due to the unfamiliarity with clinical assessment, their relative inaccessibility, requiring more surgical finesse, and the lack of experience with histopathologic examination. Obtaining a specimen sufficient for interpretation is one of the main impediments to successful diagnosis in this setting. Most pigmented bands are benign, due to more common entities such as melanocytic activation, lentigo, and/or a nevus; however, deciding which ones are due to melanoma is of the utmost importance and can be difficult. Some examples of melanoma at this site are amelanotic, which are more challenging to recognize clinically, and usually lead to significant delays in diagnosis. In order to provide optimal patient care in this setting, it is very important that the physician has an understanding of the unique clinical, surgical, and pathologic issues relating to diagnosis of melanocytic neoplasms at this site, and there is communication between the clinician and the pathologist.

SOX-10 expression in cutaneous myoepitheliomas and mixed tumors.

BACKGROUND: SOX-10 expression can be demonstrated by immunohistochemistry in salivary gland myoepitheliomas, but its expression in cutaneous myoepitheliomas and in cutaneous mixed tumors with prominent myoepithelial cells has not been studied. METHODS: We assessed the staining pattern of SOX-10 in five cutaneous myoepitheliomas and six cutaneous mixed tumors with a prominent myoepithelial component among both the myoepithelial cells and cells lining lumens. In addition, we examined the staining of S100, microphthalmia-associated transcription factor (MiTF), keratin cocktail, HMK903, smooth muscle actin (SMA) and epithelial membrane antigen (EMA). RESULTS: SOX-10 positivity was seen in three of five (60%) cutaneous myoepitheliomas and in the myoepithelial cells of all cutaneous mixed tumors. SOX-10 expression on the cells lining the glandular structures in mixed tumors was variable. All myoepitheliomas and mixed tumors stained positively with S100 and negatively with MiTF. Pan-keratin, HMK903, SMA and EMA showed variable expression. CONCLUSIONS: SOX-10 is a relatively reliable marker for staining cutaneous myoepitheliomas. Cutaneous myoepitheliomas are notoriously difficult to diagnose, and the addition of SOX-10 to the repertoire of stains that can label this tumor is of practical utility. These results further support that cutaneous myoepitheliomas and cutaneous mixed tumors exist on a morphologic and immunophenotypic spectrum.

Eruptive tumors of the follicular infundibulum presenting as hypopigmented macules on the buttocks of two Black African males.

We report two cases of eruptive tumors of the follicular infundibulum (TFI) with an unusual clinical presentation which has not been described previously in literature. In both cases, the appearance was strikingly similar, consisting of multiple asymptomatic hypopigmented macules on the buttocks of two Black African males, aged 38 and 55 years old. In both cases, the eruption had evolved over several months. The individual lesions were of similar size, approximately 1 cm, with irregular and ill-defined borders. Histopathological examination revealed a superficial and horizontal plate-like proliferation of keratinocytes emanating from the epidermis with multiple slender attachments. Pale keratinocytes were present within the epithelial plates. A Fontana stain showed a loss of melanin pigment from the epithelial plates. Orcein (elastic) stain highlighted an increase of the number of the elastic fibers surrounding the tumor. On the basis of these findings, a diagnosis of eruptive TFI was established for both cases. Among the various presentations of TFI, only the eruptive variant appears to be clinically distinctive, with asymptomatic hypopigmented macules usually located on the face, neck and upper trunk. Eruptive TFI should also be added to the clinical differential diagnosis of multiple hypopigmented macules on the buttocks of Black patients.

Calcium may preferentially deposit in areas of elastic tissue damage.

BACKGROUND: Cutaneous calcification is an acquired disorder whereby insoluble, amorphous calcium salts deposit in the skin. Classically, cutaneous calcification is categorized as metastatic, dystrophic, idiopathic, or iatrogenic. OBJECTIVE: The purpose of this study was to further elucidate the underlying pathogenic mechanism for cutaneous calcification. METHODS: Three cases of cutaneous calcification, including clinical characteristics and associated histopathology, were reviewed. Previous reports of cutaneous calcification were searched for in the published literature and included. RESULTS: Calcium is distributed within areas of underlying tissue damage (ie, locus minoris resistentiae), and in our cases, occurred specifically at sites of chronic actinic damage and intravenous extravasation tissue injury. LIMITATIONS: A small number of clinical cases and previously published reports were reviewed. CONCLUSION: We hypothesize that cutaneous calcification may preferentially occur at anatomic sites where tissue integrity has been compromised (ie, locus minoris resistentiae). We suggest one potential mechanism: that cutaneous calcification occurs within dermis that contains damaged elastic fibers. Pseudoxanthoma elasticum may serve as a possible genetic disease model for this process.

Angioinvasive Fusarium and concomitant Enterococcus infection arising in association with leukemia cutis.

Leukemia cutis represents the cutaneous infiltration of neoplastic leukocytes or their precursors that results in clinically identifiable skin lesions. For patients with myelodysplastic syndrome, developing such a lesion may indicate impending leukemic transition. These patients are also often immunocompromised, putting them at risk for infection by opportunistic fungal pathogens such as Fusarium. We describe an 85-year-old man with myelodysplastic syndrome who presented with a reddish-purple nodule with a surrounding erythematous plaque on his shin. Histopathologic examination revealed a dense diffuse infiltrate of large atypical cells in the reticular dermis, with ulceration and necrosis. Immunohistochemical studies showed positive staining with CD15, CD68 and myeloperoxidase of constituent large cells. Concurrently, there were branching and septate hyphae with occasional macroconidia-like structures throughout the infiltrate. Cultures from this lesion grew Fusarium and Enterococcus, supporting the diagnosis: leukemia cutis with superinfection involving both Fusarium and Enterococcus. To our knowledge, this is a novel report of two separate infections occurring in a lesion of leukemia cutis. This case shows that in patients with a hematologic malignancy and skin lesions, a high index of suspicion for infection is necessary when reviewing both the clinical and histopathological data to avoid overlooking an important occult infectious agent.

Gnathostomiasis in a patient who frequently consumes sushi.

A 45-year-old woman presented for evaluation of a solitary pruritic nodule on the abdomen that suddenly appeared 3 weeks before. She was healthy without a significant medical history, travel history, exposures, medications, or pets. She reported that she consumed sushi at least weekly in the city of San Francisco. A punch biopsy revealed a superficial and deep perivascular and interstitial infiltrates consisting of lymphocytes, plasma cells, and many eosinophils. Most notably, there was a parasite centered in the reticular dermis with prominent lateral chords, a well-developed muscular esophagus, and an intestine that contained a brush border and multinucleate cells. Evaluation of these histological sections by the Centers for Disease Control and Prevention determined the parasite to be a nematode of the genus Gnathostoma. The patient underwent a systemic work-up for gnathostomiasis, including imaging, and no other abnormalities were found. She completed a 3-week course of albendazole and has remained asymptomatic since the biopsy of her abdominal lesion. Although gnathostomiasis is often a systemic illness, this patient did well with apparently only localized cutaneous disease. Gnathostomiasis should be considered in patients who present with nonspecific papules and nodules, especially when there is a history of frequent consumption of raw fish.

Pathology of the Nail Unit.

This article discusses the histologic findings in key nail unit diseases, including inflammatory, infectious, and neoplastic conditions. The emphasis is on clinicopathologic correlates, best practices to demonstrate the relevant histopathologic features, and pitfalls in diagnosis. Understanding the pathology of these disorders enhances clinical acumen and may affect the choice of biopsy procedures and treatment measures, with the outcome of better clinical care for patients with nail disease.

Deferring Nail Mycological Sampling during the COVID-19 Pandemic: Recommendations from a Multidisciplinary Panel of Nail Specialists.

Onychomycosis is the most common nail condition seen in clinical practice, with significant impact on quality of life. Clinical examination alone is insufficient for accurate diagnosis, but mycological confirmation can be challenging during the COVID-19 pandemic. In this letter, a multidisciplinary panel of dermatologists, a podiatrist, dermatopathologists, and a mycologist, discuss considerations for mycological sampling during the pandemic.

Cutaneous xanthogranulomas, hepatosplenomegaly, anemia, and thrombocytopenia as presenting signs of juvenile myelomonocytic leukemia.

The development of xanthogranulomas has been linked to hematologic malignancies in children and adults, based on a number of reports in the literature. In children, a specific association between juvenile xanthogranuloma, neurofibromatosis 1, and juvenile myelomonocytic leukemia has been described. We report a case of a 9-month-old child, without a known diagnosis of neurofibromatosis 1, who presented with hepatosplenomegaly, anemia, thrombocytopenia, and multiple cutaneous nodules, which were confirmed to be juvenile xanthogranulomas upon biopsy. A concurrent work-up showed that the child had juvenile myelomonocytic leukemia. Although cutaneous juvenile xanthogranulomas are benign lesions, in several reported cases they have been shown to herald leukemia. This association between xanthogranulomas and hematologic malignancy is poorly understood. Juvenile xanthogranulomas have a number of morphologic variants and clinical presentations that can be confused with the cutaneous lesions of Langerhans cell histiocytosis and dermatofibroma. Recognition of the broad clinicopathologic spectrum of juvenile xanthogranulomas is critical for proper diagnosis.

Acquired enophthalmos in lupus erythematosus profundus.

Lupus erythematosus profundus (LEP) is an uncommon subtype of lupus erythematosus. A 76-year old man presented with inflammation of the eyelids and underlying orbital soft tissue. A biopsy disclosed inflammation and atrophy of the orbital fat consistent with LEP. Systemic corticosteroid treatment produced resolution of the inflammation. but as the edema subsided, enophthalmos became apparent. LEP should be considered in patients with a characteristic rash and orbital inflammation and may cause acquired enophthalmos.

Widespread porokeratotic adnexal ostial nevus: clinical features and proposal of a new name unifying porokeratotic eccrine ostial and dermal duct nevus and porokeratotic eccrine and hair follicle nevus.

Porokeratotic eccrine ostial and dermal duct nevus and a similar condition, porokeratotic eccrine and hair follicle nevus, are rare disorders of keratinization with eccrine and hair follicle involvement. We describe the clinical features in 5 patients, all of whom had widespread skin involvement following the lines of Blaschko. Two patients presented with erosions in the newborn period as the initial manifestation of their disease; one had an associated structural anomaly, unilateral breast hypoplasia; and one adult had malignant transformation in the nevus with development of multifocal squamous cell carcinomas. Three patients had histologic involvement of both acrosyringia and acrotrichia. Based on the observation of overlapping histologic features, we propose the name "porokeratotic adnexal ostial nevus" to incorporate the previously described entities porokeratotic eccrine ostial and dermal duct nevus and porokeratotic eccrine and hair follicle nevus.

Pustular porokeratosis.

We report a case of disseminated superficial actinic porokeratosis (DSAP) with neutrophilic pustules within cornoid lamellae on histopathologic examination, corresponding to pustules along the elevated rim clinically as well. A review of the literature identified only one other case in which pustules have been associated with porokeratosis. Our case represents an unusual variant of DSAP, which may make an ordinarily straightforward clinical diagnosis more challenging.

Isolated plantar collagenoma not associated with Proteus syndrome.

Isolated plantar cerebriform collagenomas are a relatively rare type of connective tissue nevus. They have been suggested to be pathognomonic of Proteus syndrome. However, their presence is now considered to be a major criterion of Proteus syndrome, but the diagnosis of Proteus syndrome also requires the presence of other minor criteria. We present an unusual case of an acquired plantar cerebriform collagenoma, which is not associated with Proteus syndrome. Collagenomas, or connective tissue nevi of the collagen type, represent a hamartomatous overgrowth of normal collagen. Isolated plantar collagenoma is rare, and most commonly presents in childhood. We report an interesting case of an isolated plantar cerebriform collagenoma in an adult.

IgM-lambda paraproteinemia with associated cutaneous lymphoplasmacytic infiltrate in a patient who meets diagnostic criteria for POEMS syndrome.

POEMS is a rare multisystem paraneoplastic syndrome featuring polyneuropathy, organomegaly, endocrinopathy, a monoclonal protein, and skin changes. In the relatively few reported biopsies of POEMS-associated cutaneous hyperpigmentation, the most common skin finding seen in patients with the disorder, only a non-specific inflammatory infiltrate has been demonstrated histologically. We present the case of a 79-year-old man with polyneuropathy, autoimmune thyroiditis, pancytopenia, and a history of lymphadenopathy who presented to the inpatient dermatology service with cutaneous hyperpigmentation. A skin biopsy of a hyperpigmented area showed a cutaneous lymphoplasmacytic infiltrate, prompting further investigation. A monoclonal IgM-lambda paraprotein was subsequently identified, leading to administration of combination chemotherapy for a diagnosis of POEMS syndrome. The novel finding of a lymphoplasmacytic infiltrate in POEMS-associated hyperpigmentation suggests a diagnostic role for skin biopsy in these patients.