Onychocytic Matricoma: A Clinical, Dermoscopic, and Pathological Analysis of 14 Cases.

ABSTRACT: Onychocytic matricoma (OCM) is a benign neoplasm of the nail matrix. Only 18 cases of this tumor have been reported in the literature to date. We retrospectively analyzed the clinical features of 14 patients with OCM. The most common clinical feature was longitudinal xanthopachyonychia (n = 9), followed by longitudinal leukopachyonychia (=3) and longitudinal pachymelanonychia (n = 2). The most common clinical findings identified following dermoscopy and analysis at high magnification of classical photographs were free-edge thickening of the nail plate without pitting (n = 14), longitudinal ridging (n = 7), round white clods (n = 7), white dots (n = 7), and filiform hemorrhages (n = 7), followed by oval and linear white clods (n = 5), fuzzy lateral border (n = 5), and red-purple blood clods (n = 3). Nail clipping histopathology showed a thickened nail plate with multiple, small, round-to-oval spaces. The tumor expressed immunopositivity for LEF-1. Dermoscopy of the nail plate and nail clipping histology provides useful information with regards to the differential diagnosis with subungual squamous cell carcinoma and nail melanoma. Ex vivo-in vivo correlation facilitates a better dermoscopic assessment of this unique underrecognized disease. However, the differential diagnosis between OCM and onychocytic carcinoma requires biopsy of the tumor. LEF-1 as an onychogenic marker can be used to resolve the differential diagnosis between OCM and subungual longitudinal acanthoma/seborrheic keratosis.

Tumor of follicular infundibulum - reappraisal in a series of 28 patients with critical review of the literature.

BACKGROUND AND OBJECTIVES: Tumor of follicular infundibulum (TFI) has been described as a neoplasm - isolated and multiple - and in association with other lesions. Its histopathologic definition is controversial. PATIENTS AND METHODS: We present a histopathologically analyzed series of 28 patients with TFI features. This has been supplemented by a search in MEDLINE on the literature on this subject. The corresponding figures given in these articles have been discussed and analyzed. RESULTS: Patients comprised 16 women and twelve men. TFI features were seen in five patients with nevus sebaceous, two trichofolliculomas, one dilated pore Winer, eight viral warts, one dermatofibroma, six seborrheic keratoses, three actinic keratoses, one invasive squamous cell carcinoma, and one basal cell carcinoma in association with a squamous cell carcinoma/actinic keratosis. After study of the literature especially of solitary cases of TFI, we interpret such cases mostly as variants of seborrheic keratoses with variable degree of infundibular, isthmic and/or sebaceous differentiation with or without regression. CONCLUSIONS: We regard TFI as an epithelial growth pattern which may occur in hamartomatous, inflammatory, infectious, reactive, or neoplastic conditions, in most solitary forms likely best classified within the histopathological spectrum of seborrheic keratoses.

Diagnostic utility of SOX10 immunostaining in benign lichenoid keratosis: A study of 21 cases.

BACKGROUND: Benign lichenoid keratosis (BLK) is a cutaneous lesion that can clinically mimic malignancy and may represent regression of a pre-existing lesion. BLK may show epidermal pseudo-nests prompting evaluation for a melanocytic lesion. False positivity of MART-1/Melan-A immunostaining in pseudonests has been showed; however, the value of SRY-related HMG-box 10 (SOX10) staining in BLK with features suspicious for a melanocytic proliferation has not been previously reported. METHODS: Twenty-one cases of BLK from 2015 to 2020 were identified. Slides were reviewed and SOX10 immunohistochemistry was performed on each case. Subsequently, Melan-A immunohistochemical staining was performed on all cases. RESULTS: In 10 cases (47.6%), unexpected SOX10 staining was seen in rare to numerous small, single cells in the epidermis above the basal cell layer. No malignancy was identified. Of the 10 cases, 8 (80%) showed suprabasal SOX10 staining did not show similar suprabasal Melan-A staining; 2 (20%) cases showed scattered suprabasal cells positive for Melan-A. CONCLUSION: SOX10 immunostaining in BLK can highlight scattered cells in the epidermis (not easily noticeable on routine stain). Performing SOX10 immunostain alone on BLK can prompt a misdiagnosis of a melanocytic lesion and should be done with caution.

Condyloma and coincidental epidermodysplasia verruciformis acanthoma positive for human papillomavirus-14 and -21.

Epidermodysplasia verruciformis (EDV) is a rare genodermatosis that predisposes individuals to persistent infection with ß-human papillomavirus (HPV) genotypes. The term EDV acanthoma may be applied to lesions with incidental findings of EDV-defining histopathological features without clinical signs of EDV. We report a case of HPV-14- and -21-positive EDV acanthoma arising in association with condyloma in a female patient with a history of low-grade squamous intraepithelial lesion of the cervix positive for high-risk HPV (non-16/18), chronic kidney disease, and systemic lupus erythematosus. The patient had no family or personal history of EDV, but the patient was on immunosuppressive therapy with mycophenolate mofetil and prednisone. A biopsy specimen from one of the perianal lesions revealed histopathologic changes consistent with EDV in the setting of condyloma. Molecular testing showed HPV-14 and -21, which supported the coexistence of condyloma with EDV acanthoma.

Clear Cell Acanthoma: A Series of 70 Cases. / Acantoma de células claras. Estudio clínico de 70 pacientes.

BACKGROUND AND OBJECTIVE: Clear cell acanthoma (CCA) is an uncommon lesion histologically characterized by the presence of epidermal acanthosis with keratinocytes containing clear cytoplasm. Although many single cases of CCA have been described, few case series have been published. The aim of this study was to describe the clinical characteristics of CCA in our practice setting. MATERIAL AND METHODS: Retrospective study of patients diagnosed with CCA at Hospital Universitario de Bellvitge in Barcelona, Spain, between 1995 and 2021. We conducted a chart review to record age, sex, number and location of lesions, diameter, time since onset, clinical characteristics, suspected clinical diagnosis, and treatment. RESULTS: Seventy patients (30 women and 40 men) with a mean (SD) age of 62 (13) years were diagnosed with CCA during the study period. Median (interquartile range) time since onset was 2 (4) years and median lesion diameter was 6 (5) mm. One woman had multiple lesions. Lesions were located on the lower extremities in 57 patients (81%), the posterior aspect of the trunk in 8 (11%), the anterior aspect of the trunk in 4 (5%), and the upper extremities in 1 (1%). CCA was clinically suspected in 40% of patients seen by dermatologists. CONCLUSIONS: CCA presents as an erythematous, dome-shaped lesion with pinpoint vessels and an epidermal collarette. The accuracy of clinical diagnosis has improved relative to earlier series, possibly due to a better clinical understanding of this lesion and a greater use of dermoscopy.

Comparative study of treatment methods for benign lichenoid keratosis of the face.

Benign lichenoid keratosis is one of the most common skin lesions that develop on the faces of middle-aged women. This study aimed to find an effective treatment method for benign lichenoid keratosis. A total of 49 patients, who had a positive diagnosis during 2010-2018, were enrolled in the study. An Investigator's Global Assessment of the lesion was done using the 5-point visual analog scale to evaluate treatment efficacy. After excluding subjects who did not have a follow-up photograph, 38 subjects were given an Investigator's Global Assessment score. Combination therapy using laser and a topical agent was useful in the management of benign lichenoid keratosis on the face. Ablative laser was effective for immediate improvement of the lesion, whereas non-ablative laser was also useful and showed several benefits over ablative laser. Optimal treatment should be decided after considering the patient's preference, compliance with treatment regimen, and skin type.

Follicular Porokeratoma: Report of a New Variant of Porokeratoma (Porokeratotic Acanthoma) and Literature Review.

ABSTRACT: Porokeratoma is a rare type of epidermal acanthoma, of which 22 cases have been published in the literature. It is characterized by the presence of multiple cornoid lamellae embedded within a single verrucous or keratotic nodule. Despite this histologic feature being shared with porokeratosis, the etiopathogenesis of porokeratoma and its relationship with porokeratosis remain unclear. We report a new case of porokeratoma involving hair follicles, a finding that has been reported in only one of the previously published cases. Analogous to follicular porokeratosis, a form of porokeratosis involving hair follicles, we have termed this lesion "follicular porokeratoma." A review of all 23 published cases (including the present case) is also provided.

Comparative Immunohistochemical Study of Hidroacanthoma Simplex and Clonal Seborrheic Keratosis With GATA3 and p63.

ABSTRACT: Histopathologically both hidroacanthoma simplex (HS) and clonal seborrheic keratosis (CSK) are characterized by intraepidermal nests of tumor cells. Although they show subtle microscopic differences, they can be difficult to accurately differentiate. Previous immunohistochemical studies have been inconclusive. We conducted an immunohistochemical study with GATA3 and p63 on cases of HS and CSK tentatively identified by their microscopic appearances and cases of eccrine poroma and seborrheic keratosis as their respective controls. The clinical, histopathological, and dermoscopic findings of these cases were also reviewed. All cases of HS and poroma were negative for GATA3, whereas all cases of CSK and seborrheic keratosis were positive for GATA3. HS, CSK, and their controls were all positive for p63. Microscopic, clinical, and dermoscopic differences were also found between HS and CSK. Our study demonstrated that GATA3 is useful for differentiating HS from CSK. Our initial microscopic observations also proved to be reliable, but immunostaining with GATA3 is helpful for confirming the diagnosis or establishing the diagnosis of uncertain cases. Awareness of the clinical and dermoscopic features of these 2 entities could also avoid misdiagnosis based solely on pathological observation.

Pilomatrical Acanthoma: An Extremely Rare Intraepidermal Variant of Pilomatricoma.

ABSTRACT: Pilomatrical differentiation can be observed in a variety of benign and malignant tumors, with the most common prototype being pilomatricoma. Pilomatricoma often presents in the deep dermis or subcutis, and the sole involvement of epidermis is extremely rare. In our current case series, specimens from 5 patients were included with an average age of 68 years. All lesions presented as solitary verrucous or keratotic papules on the extremities, with 1 lesion having a prominent horn. All lesions have a variable mixture of basaloid matrical cells and shadow cells, and all lesions express ß-catenin (strong nuclear and cytoplasmic), lymphoid enhancer-binding factor 1 within the matrical component, and pleckstrin homology-like domain family A member 1. The histomorphology and immunoprofile of all lesions are of pilomatrical differentiation, confined to the level of the epidermis. Based on these findings and analogous to the terminology used for other benign intraepidermal proliferations (hidroacanthoma simplex and epidermolytic acanthoma), we propose the term "pilomatrical acanthoma" for these rare lesions.

Dermoscopic findings and histopathological correlation in large cell acanthoma.

Since large cell acanthoma (LCA) has many overlapping clinical and histopathological features with other epidermal pigmented tumours, an additional method to differentiate it would be of great clinical significance. A retrospective study was performed on 33 lesions (26 patients) to identify distinct dermoscopic findings of LCA and to describe dermoscopic-histopathological correlations. The results revealed that dermoscopy significantly aids in the distinction of LCA from other epidermal tumours included in the differential diagnosis. Yellow opaque homogeneous background, brown dots, and moth-eaten border are common findings, and prominent skin markings and short white streaks are additional distinguishing features. Several important findings that are common in other diseases are rare in LCA.

A conscious minimally invasive approach to remove follicular cysts and infundibular keratinizing acanthomas in five dogs.

Follicular cysts and infundibular keratinizing acanthomas are common benign cutaneous lesions in dogs. Current treatment options include surgical excision under general anaesthesia, cryotherapy, carbon dioxide laser and retinoids, each with potential disadvantages. We describe a conscious, minimally invasive, surgical excision procedure with high success rate and no complications in five dogs.

Les kystes folliculaires et les acanthomes kératinisant infundibulaires sont des lésions cutanées bénignes fréquentes chez le chien. Les options de traitement actuelles comprennent l'exérèse chirurgicale sous anesthésie générale, la cryothérapie, le laser au dioxyde de carbone et les rétinoïdes, chacun présentant des inconvénients potentiels. Nous décrivons une procédure d'exérèse chirurgicale consciente, peu invasive, avec un taux de réussite élevé et aucune complication chez cinq chiens.

Los quistes foliculares y los acantomas queratinizantes infundibulares son lesiones cutáneas benignas comunes en perros. Las opciones de tratamiento actuales incluyen la escisión quirúrgica bajo anestesia general, crioterapia, láser de dióxido de carbono y retinoides, cada uno con posibles desventajas. Describimos un procedimiento de escisión quirúrgica consciente, mínimamente invasivo, con una alta tasa de éxito y sin complicaciones en cinco perros.

Cistos foliculares e acantomas infundibulares queratinizantes são lesões cutâneas benignas em cães. As opções terapêuticas existentes atualmente são excisão cirúrgica sob anestesia geral, crioterapia, laser de dióxido de carbono e retinoides, cada um com desvantagens potenciais. Nós descrevemos aqui um procedimento de excisão cirúrgica minimamente invasivo, consciente, com um grande potencial de sucesso e sem complicações em cinco cães.

Cutaneous acantholytic dyskeratotic acanthoma accompanying syringofibroadenomatous hyperplasia with proliferation of mature sebocytes: A case report.

Acantholytic dyskeratotic acanthoma is a rare variant of epidermal acanthoma. It has a flat, plaque-like structure and is characterized microscopically by acantholysis and dyskeratosis. Eccrine syringofibroadenomatous hyperplasia is benign and likely reactive. It has recently been considered as a hyperplastic process affecting the eccrine ducts rather than the neoplasm because of its pathological heterogeneity and wide clinical associations. In this article, we present the case of 97-year-old Japanese women with a 10-mm wide, painful acantholytic dyskeratotic acanthoma accompanied by syringofibroadenomatous hyperplasia in the right femoral region. Although syringofibroadenomatous hyperplasia is known to occur as a reactive process with various dermatoses and cutaneous tumors, to date, there have been no reports of cases of acantholytic dyskeratotic acanthoma accompanying syringofibroadenomatous hyperplasia. Moreover, this case also includes the unusual finding of an increase in the mature sebocytes in the area of the syringofibroadenomatous hyperplasia.

Hypergranulotic Dyskeratotic Acanthoma: Another Histologically Distinctive Acanthoma.

ABSTRACT: Various acanthomas have been named based on their distinctive histopathologic patterns. Hypergranulotic dyskeratotic acanthoma represents another acanthoma with a distinctive histopathologic pattern that has been rarely reported. In this article, clinical and histological features of hypergranulotic dyskeratotic acanthoma are delineated. A retrospective analysis was performed of cases with diagnosis or suggested diagnosis of hypergranulotic dyskeratotic acanthoma between 2012 and 2017 from 2 dermatopathology laboratories. Forty-eight potentials were identified, of which 18 cases met the inclusion histologic criteria. Most cases came from women (78%) with a mean age of 53 years, and the thigh was the most common site involved. All cases had the following histopathological findings: (1) verrucous or digitated epidermal hyperplasia, (2) hyperkeratosis dominated by basketweave or compact orthokeratosis, (3) hypergranulosis involving the breadth of the lesion, and (4) presence of enlarged, often indistinctly bordered, keratinocytes with cytoplasm characterized by a blue-gray granular peripheral zone sometimes showing outstretched desmosomes and central perinuclear eosinophilic zones, a combination of findings representing slowly evolving dyskeratosis. Retrospective nature and a small sample size are the major limitations of the study. In sum, hypergranulotic dyskeratotic acanthoma can be easily distinguished from other acanthomas based on their repeatable histopathological findings.

Hyaline Inclusion Acanthoma.

ABSTRACT: Eosinophilic hyaline inclusions (EHIs) or globules have been reported in various cutaneous tumors including vascular lesions, myoepithelial neoplasms, and basal cell carcinoma. In basal cell carcinoma, the presence of intracytoplasmic inclusions is reportedly associated with myoepithelial differentiation. In this regard, EHI has not been conclusively documented in a cutaneous lesion of genuine squamous cell lineage without aberrant differentiation. In the current case, a biopsy from the right thigh of a 71-year-old male patient demonstrated a relatively well-demarcated intraepidermal squamous lesion featured an admixture of predominantly enlarged keratinocytes harboring distinct eccentric intracytoplasmic EHI and a smaller population of keratinocytes displaying pale cytoplasm. Cytologic atypia, mitotic activity, and inflammatory cells were not identified. The intracytoplasmic EHI stained red with Masson's trichrome and were negative with periodic-acid Schiff with and without diastase. Immunologically, the lesion was strongly and diffusely positive for various cytokeratins but negative for ubiquitin and myoepithelial markers. Only cytokeratin AE1 revealed a differential staining pattern as the suprabasal lesional cells displayed significantly stronger immunoreactivity in comparison with the adjacent normal keratinocytes. Polymerase chain reaction for low-risk and high-risk human papillomavirus was negative. Molecular studies did not reveal any mutations commonly encountered in seborrheic or lichenoid keratoses. As an analogous lesion has not previously reported in the literature, the term hyaline inclusion acanthoma is proposed for this peculiar lesion.

Clear Cell Proliferations of the Skin: A Histopathologic Review.

ABSTRACT: Cutaneous clear cell proliferations encompass a heterogenous group of several primary cutaneous neoplasms and metastatic tumors with different histogenesis. Many of these clear cell proliferations may seem strikingly similar under the microscope resulting in challenging diagnosis. In many of these clear cell lesions, the reason for the clear or pale appearance of proliferating cells is unknown, whereas in other ones, this clear cell appearance is due to intracytoplasmic accumulation of glycogen, mucin, or lipid. Artifacts of tissue processing and degenerative phenomenon may also be responsible for the clear cell appearance of proliferating cells. Awareness of the histopathologic findings as well as histochemical and immunohistochemical techniques are crucial to the accurate diagnosis. This review details the histopathologic features of clear cell cutaneous proliferations, classifying them according their type of differentiation and paying special attention to the histopathologic differential diagnosis among them.

Clear cell acanthoma.

Clear cell acanthoma is a rarely diagnosed tumor with variable clinical morphology that is usually only recognized by its histopathological features. The primary lesion is a red papule a few millimeters in diameter that often occurs as a single lesion on the lower extremities. In dermoscopy, resemblance of the vessels to a string of pearls is a largely specific finding of clear cell acanthoma. In contrast to the initially uncharacteristic clinical findings, histopathology of clear cell acanthomas is characterized by a typical compact, well-demarcated acanthosis consisting of pale-staining, PAS-reactive keratinocytes. As etiology and pathogenesis are both unclear, nosology of clear cell acanthoma is also controversial, with an ongoing debate as to its classification as cutaneous neoplasia or reactive inflammatory dermatosis.

Response of pruritic scrotal epidermolytic acanthomas to pimecrolimus 1% cream.

Epidermolytic acanthomas (EA) are rare benign tumors of unclear etiology that present as flat, sometimes slightly keratotic, pale or whitish papules that are usually asymptomatic. Not uncommonly, their clinical appearance in the anogenital area might lead to misdiagnosis as other lesions that commonly develop at this site, such as condylomata acuminata. Though mainly asymptomatic, there are also reports of EA presenting with persistent genital pruritus. We describe the first reported case of pruritic scrotal EA successfully treated with topical pimecrolimus.

Multiple Epidermolytic Acanthomas: Rare Vulval Lesions Which May be Mistaken for Viral Warts.

Epidermolytic acanthoma is a rare benign lesion that most often presents as a solitary or multiple small papular lesions on the trunk, face, limbs or external male genitalia. Only a small number of cases have been reported occurring on the vulva and clinically and histologically they may mimic and be misdiagnosed as viral warts. We report 2 cases of multiple epidermolytic acanthomas localized to the vulva. Molecular tests (in situ hybridization and polymerase chain reaction) showed no evidence of human papillomavirus infection and p16 staining was negative. We stress the need for pathologists to consider epidermolytic acanthoma in the differential diagnosis of multiple vulval lesions resembling viral warts.

Epidermolytic acanthoma in a young woman: a case letter.

Epidermolytic acanthoma (EA) is a rare benign tumor that is characterized by epidermolytic hyperkeratosis on histopathology. It usually presents in adulthood as an asymptomatic tumor <1 cm in diameter with a verrucous surface. We report a very uncommon case of epidermolytic acanthoma. A 21-year-old woman came to our hospital with a pale black papule on the left lower eyelid near the Inner canthus for 2 months. Two months ago the patient noted a pale brown spot on the inside of the left lower eyelid, which gradually enlarged, forming a papule with a deepened color. There were no associated symptoms, such as itching or pain. There were no local injuries, scratches, or other incidents before the crash occurred. The patient was always healthy, with no history of chronic disease or other skin diseases, and no similar cases existed in the family. We diagnosed it as EA.

Mutations in KRT10 in epidermolytic acanthoma.

BACKGROUND: Epidermolytic acanthoma (EA) is a rare acquired lesion demonstrating a characteristic histopathological pattern of epidermal degeneration referred to as epidermolytic hyperkeratosis (EHK). On histopathological analysis, EA appears nearly identical to inherited EHK-associated dermatoses such as epidermolytic ichthyosis and ichthyosis bullosa of Siemens. While it has been speculated that EA is caused by mutations in KRT10, KRT1, or KRT2 found in these inherited dermatoses, none have yet been identified. Herein, we aim to identify the contributions of keratin mutations to EA. METHODS: Using genomic DNA extracted from paraffin-embedded samples from departmental archives, we evaluated a discovery cohort using whole-exome sequencing (WES) and assessed remaining samples using Sanger sequencing screening and restriction fragment length polymorphism (RFLP) analysis. RESULTS: DNA from 16/20 cases in our sample was of sufficient quality for polymerase chain reaction amplification. WES of genomic DNA from lesional tissue revealed KRT10 c.466C > T, p.Arg156Cys mutations in 2/3 samples submitted for examination. RFLP analysis of these samples as well as eight additional samples confirmed the mutations identified via WES and identified four additional cases with Arg156 mutations. In sum, 6/11 screened cases showed hotspot mutation in KRT10. CONCLUSIONS: Hotspot mutations in the Arg156 position of KRT10, known to cause epidermolytic ichthyosis, also underlie EA.