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Until now, the skin findings reported in association with coronavirus disease 2019 (COVID-19) infection remain sparse, nonspecific, and devoid of any prognostic significance.1,2 This case report emphasizes a novel cutaneous sign of utmost importance for dermatologists to recognize.

Adenomatoid tumors are benign tumors of mesothelial origin that are usually encountered in the genital tract. Although they have been observed in other organs, the skin appears to be a very rare location with only one case reported in the literature to our knowledge. We report a second case of an adenomatoid tumor, arising in the umbilicus of a 44-year-old woman. The patient presented with an 8 months old erythematous and firm plaque under the umbilicus. A skin biopsy showed numerous microcystic spaces dissecting a fibrous stroma and being lined by flattened to cuboidal cells with focal intraluminal papillary formation. This poorly known diagnosis constitutes a diagnostic pitfall for dermatopathologists and dermatologists, and could be misdiagnosed as other benign or malignant entities. Through this case report, a practical approach and diagnostic keys have been devised to avoid misdiagnosis and overtreatment. This article is protected by copyright. All rights reserved.

Resume Introduction Le fibromyxome acral superficiel (FMAS) est une tumeur benigne des tissus mous de localisation acrale, generalement peri- ou sous-ungueale. Une localisation sous-matricielle n’a pas, a ce jour, ete decrite. Observation Nous rapportons la presentation clinique et histologique de trois cas de FMAS purement sous-matriciels. Les patients presentaient un pseudo-hippocratisme digital, une onychogryphose isolee ou une macro-lunule triangulaire. L’aspect histopathologique etait typique. Discussion Le FMAS se presente comme un nodule ferme, de couleur chair, de croissance lente, douloureux ou non, localise aux extremites, en particulier dans la region ungueale. Microscopiquement, il s’agit d’une tumeur dermique relativement bien circonscrite mais non encapsulee, composee de cellules fusiformes integrees dans une matrice myxocollagenique, envahissant parfois l’hypoderme. Les cellules tumorales expriment de facon diffuse le CD34. Une approche chirurgicale conservatrice est indiquee. Le FMAS doit etre connu des cliniciens et des pathologistes afin d’eviter des erreurs diagnostiques qui pourraient conduire a des actes chirurgicaux inutilement delabrants. Conclusion La localisation sous-matricielle du FMAS est inhabituelle et caracterisee par un pseudo-hippocratisme digital, une onychogryphose isolee ou une macro-lunule triangulaire. Une approche chirurgicale conservatrice doit etre recommandee.

When dealing with nails, pathologic examination is often indispensable to reach an accurate diagnosis. This requires a biopsy correctly performed by the dermatologist, a specimen correctly handled in the pathology lab, and a pathologist with good knowledge of the various nail conditions. The normal nail histology is first described in this paper. The pathologic aspects of melanocytic lesions, nonmelanocytic tumors of the nail apparatus, inflammatory nail conditions, and onychomycosis are then considered, together with their main differential diagnoses.

Inflammatory and subcutaneous nodules can arise in treated and untreated cases of Whipple disease (WD). The inflammatory immune reconstitution syndrome describes paradoxical clinical inflammatory worsening of a preexisting condition because of a return of immune function. Clinicopathologic examination of 4 patients with WD who presented with erythema nodosum leprosum (ENL)-like lesions and the findings of a systematic review of this phenomenon revealed that ENL-like lesions occurred in predominantly middle-aged male patients who suffered from WD, mostly on the legs. Patients showed a nonvasculitic, mostly septal panniculits with neutrophils, macrophages, and lymphocytes. Numerous bacteria-laden periodic acid-Schiff + macrophages and free bacilli were detected in the dermis, as well as subcutaneous septae and adipose lobules. These lesions occurred in both untreated and treated patients as part of inflammatory immune reconstitution syndrome. In conclusion, ENL-like lesions represent a characteristic histopathologic pattern associated with WD, which can occur in different contexts whenever there is a change in the immunological status of the patient. This change can be triggered by antimicrobial treatment, immunomodulatory and immunosuppressant therapy, or occur spontaneously, rarely.

The etiology of longitudinal melanonychia (LM) is difficult to establish by clinical and dermoscopic examinations alone. Microscopic examination of the nail matrix remains crucial. Two groups of LM may be identified: melanocytic activation (melanic pigmentation of the matrix epithelium without any increase in the density of melanocytes) and melanocytic proliferation (lentigo, nevus, or melanoma). The histological examination is challenging, and immunohistochemical investigations can be helpful. The objective of this study was to analyze the immunohistochemical findings with routinely used markers in melanocytic tumors-S-100 protein, HMB-45, and Melan-A-in LM. A series of 40 cases were analyzed: 10 activations, 4 lentigines, 7 nevi, 12 in situ melanomas, and 7 invasive melanomas. The sensitivity of S-100 protein is weak in benign and malignant intraepithelial melanocytes of the nail matrix, and if this marker is performed alone, it may be wrongly reassuring. However, the use of S-100 protein is essential to differentiate invasive melanoma, lacking an intraepithelial component, and particularly desmoplastic melanoma, from epithelial and mesenchymal tumors. HMB-45 and Melan-A are more sensitive than S-100 protein for the evaluation of intraepithelial melanocytic proliferation of the nail apparatus, with HMB-45 being the most intense marker. In the dermal component, HMB-45 and Melan-A were less sensitive than S-100 protein. In conclusion, we recommend that the panel of antibodies used for histological evaluation of LM should include HMB-45 and/or Melan-A and S-100 protein only if an invasive melanoma is suspected.

Resume Introduction La survenue de granulomes visceraux ou cutanes au cours de certains deficits immunitaires est une notion bien etablie, notamment avec le deficit immunitaire commun variable (DICV). Nous rapportons le cas d’un enfant immunodeficient atteint de granulomes cutanes predominant sur la face. Observation Un garcon âge de six ans et neuf mois, souffrant d’un deficit immunitaire de nature a ce jour indeterminee, nous etait adresse pour des lesions cutanees progressivement evolutives de la face et du pied droit. Des investigations paracliniques tres larges etaient realisees pour exclure un processus infectieux ou neoplasique ; elles se revelaient negatives, tandis qu’une biopsie cutanee confirmait la presence de granulomes. Une corticotherapie generale etait instauree sans reel succes, puis remplacee progressivement par un anti-TNFα. Apres six mois de ce traitement, les lesions avaient completement regresse et elles n’avaient pas recidive six mois apres son arret. Conclusion L’originalite de notre observation reside dans sa presentation, mettant en scene le developpement de granulomes cutanes dans un contexte de deficit immunitaire d’une variete a ce jour non identifiee mais non classee comme DICV, ainsi que dans son aspect therapeutique, par l’utilisation des biotherapies avec succes.

A female newborn presented with a congenital urticarial rash that consisted of fluctuating well-demarcated pink or pale reddish macules or slightly raised papules and plaques. In addition, purulent cerebrospinal fluid was present in the absence of evidence of congenital infection. Skin biopsy revealed a sparse infiltrate throughout the entire dermis, including the eccrine adventitia. The infiltrate was composed mostly of neutrophils, but rarely lymphocytes and eosinophils could also be seen. No vasculitis was present. Because of the presenting attributes, a diagnosis of cryopyrin-associated periodic syndrome (CAPS) was considered and the neonatal-onset multisystem inflammatory disorder (NOMID) that represents the most severe expression of the CAPS clinical spectrum was favored. Diagnosis was confirmed by identification of a mutation in the cold-induced autoinflammatory syndrome-1 gene and by an observed response to treatment with the interleukin-1 receptor antagonist anakinra. Both the clinical and histopathological findings of the presented case may represent a distinct entity within the spectrum of aseptic neutrophilic dermatitis. We refer to this spectrum as neutrophilic urticarial dermatosis (NUD), which may serve as a cutaneous marker of autoinflammation. NUD with perieccrine involvement should prompt consideration of CAPS, especially NOMID, in the context of neonatal multisystem disease.

We present a case of congenital juvenile xanthogranuloma (JXG) with both cutaneous and renal involvement. Skin lesions consisted of bluish papules and nodules (blueberry muffin baby) located on the head, trunk and proximal extremities. Subsequent investigations revealed a renal mass. Histopathology of both cutaneous and renal specimens was consistent with JXG. Both clinical presentation and extracutaneous localization were remarkable.

Tumors of the nail unit may be difficult to diagnose because of the screening effect of the nail plate. In longitudinal melanonychia, several new promising techniques assist with early diagnosis of melanoma (in vivo matrix dermoscopy and immunohistochemistry) as well as sparing as much of the healthy tissues as is possible (shave biopsy technique). Diagnosing nail disorders is in some instances difficult both for the clinician and the pathologist. New tools such as polymerase chain reaction have been proposed for onychomycosis, which accounts for more than half of nail conditions, will allow quick and accurate diagnosis. However, polymerase chain reaction analysis remains expensive and is not routinely used by clinicians. Scoring nail dystrophy by clinical observation remains very subjective; therefore, severity indexes have been proposed. Another emerging noninvasive technique is forensic analysis of nail clippings for detection of drug intake and abuse, as well as exposure to environmental pollution.

POEMS syndrome (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, skin disorders) is a rare multisystemic disease associated with plasma cell dyscrasia. A 68-year-old woman with chronic renal insufficiency and arterial hypertension included in her medical history was admitted to the hospital with confusion, somnolence and asthenia. She presented ascites, hepatosplenomegaly, leg oedema, distal dysesthesias, leuconychia and multiple nodular purple red angiomas on the trunk, upper limbs and fingers. Hypothyroidism was revealed in the laboratory investigations and monoclonal IgG peak in immunoelectrophoresis. Electromyography showed both demyelinisating and axonal degenerative neuropathy. The diagnosis of POEMS syndrome was based on the dermatopathological examination of a cutaneous angioma; histology revealed features of glomeruloid angioma, a specific marker of this syndrome.

Background Nail apparatus melanoma (NAM) is a rare melanocytic neoplasm with pejorative prognosis often related to late diagnosis. Early diagnosis at in situ stage (NAMis) is difficult, but essential to improve prognosis. NAMis management is not well established yet. Removal of the whole nail unit has been advocated in several small series as a potential treatment for NAMis. Objective To report and assess 'functional' or 'conservative' surgery for NAMis and evaluate its long-term oncologic safety. Methods Retrospective study of cases diagnosed in the University Hospital Saint-Pierre collected over a 13 year period and compared with the published data. Results Eleven cases of NAMis were identified: 73% concerned females. Thumb and first toe were the most affected digits (63% of total). Monodactylic longitudinal melanonychia (LM) was the most frequent presentation (92%). Mean diagnosis delay was 5 years. Diagnosis was suspected on the basis of clinical and dermatoscopic signs and was confirmed by pathological examination. All patients underwent complete nail unit removal with 6 mm security margins around the anatomic boundaries of the nail. Two late local recurrences were observed at 7 and 11 years follow-up. Conclusions Our series, the largest up to now, demonstrates that 'functional surgery' is a rational approach for NAMis with an excellent oncologic safety at 5 years. However, this study suggests that a very long-term follow-up is mandatory, as recurrences may appear late. © 2013 European Academy of Dermatology and Venereology.

Background Squamous cell carcinoma (SCC) is the most common malignant tumor at the nail unit. It mainly affects middle-aged men, with a peak incidence between 50 and 69 years of age. Diagnosis is often delayed because of the slow evolution of the lesion and multiple clinical features. Objective We sought to characterize the different clinical and histopathological patterns of SCC of the nail unit and evaluate their therapeutic outcome. Methods Records for 58 patients were retrieved from our department's dermatopathology database over a period of 15 years (1995-2011) and the patients recontacted. Results Of the 58 patients, 51 were eligible for follow-up. There was a male predominance (72.5%). The fingers were most commonly affected (98%), the right index and long fingers being most commonly affected (20.8% each). The nail bed was mainly affected. The commonest clinical signs were, in decreasing order, subungual hyperkeratosis, onycholysis, oozing, and nail plate destruction. The majority of SCC of the nail unit was in situ (63%). The recurrence rate of all treatments taken together was 30.6%. Limitations Retrospective study design is a limitation. Conclusions SCC of the nail unit mostly affects men aged 50 to 69 years. Most cases were the warty type, with oozing being an underrecognized clinical sign. Contrary to prior studies, most lesions were in situ, and bone involvement was uncommon. Conservative surgical resection should be the first-line treatment when the bone is not involved. Recurrence rate is high when a procedure other than Mohs micrographic surgery is performed.

Objectives We sought to assess the shave biopsy technique, which is a new surgical procedure for complete removal of longitudinal melanonychia. We evaluated the quality of the specimen submitted for pathological examination, assessed the postoperative outcome, and ascertained its indication between the other types of matrix biopsies. Design This was a retrospective study performed at the dermatologic departments of the Universities of Liege and Brussels, Belgium, of 30 patients with longitudinal or total melanonychia. Results Pathological diagnosis was made in all cases; 23 patients were followed up during a period of 6 to 40 months. Seventeen patients had no postoperative nail plate dystrophy (74%) but 16 patients had recurrence of pigmentation (70%). Limitations This was a retrospective study. Conclusions Shave biopsy is an effective technique for dealing with nail matrix lesions that cause longitudinal melanonychia over 4 mm wide. Recurrence of pigmentation is the main drawback of the procedure.

Basal cell carcinoma (BCC) is the most common malignant skin tumour. In the last few years, the incidence of multiple BCC has also increased in young patients. We describe the clinical case of a young 29-year-old woman who developed 7 BCC on her abdomen during her first pregnancy and 4 other similar tumours 2 years later during her second pregnancy, all located on the abdomen. Polymerase chain reaction revealed the presence of numerous human papillomavirus DNA sequences. To our knowledge, such a clinical presentation has not been previously reported. Different physiopathological considerations are discussed.

We report a case of a cutaneous Mycobacterium chelonae infection on the dorsum of the forearm of a patient undergoing chronic hemodialysis. The infection showed a linear and distal extension. This unusual distal dissemination was apparently secondary to a venous reflux, a circulatory repercussion of the patient’s arteriovenous fistula.

Acantholytic dyskeratotic acanthomas of the skin have been recently described in several publications. They differ from acantholytic acanthomas by the presence of dyskeratosis. However these tumors have never been described in nails. We report three cases localized on the thumb nail.

The so-called perivascular epithelioid cell neoplasm (PEComa) family includes angiomyolipoma, clear cell 'sugar' tumor (CCST), lymphangioleiomyomatosis, and clear cell myomelanocytic tumor (CCMMT). These rare tumors are characterized by the co-expression of melanocytic and muscle markers. They have been recognized in an increasing number of sites but currently only one case of PEComa, of the CCMMT subtype, has been reported in the skin in abstract form. We provide the clinicopathologic description of a case of extrapulmonary CCST located in the dermis and superficial subcutis of the thigh of a 60-year-old female. The lesion was composed of nests of epithelioid and spindle cells with abundant clear to granular cytoplasm and distinct cell borders. The tumor showed strong and diffuse immunoreactivity with HMB-45. Scattered cells expressed desmin and h-caldesmon. Antibodies to S-100 protein, melan-A, cytokeratins, and smooth muscle actin were negative. This first case of cutaneous PEComa of the CCST type expands the differential diagnosis of clear cell/granular cell tumors of the skin.

Superficial acral fibromyxoma (SAFM) is a recently recognized myxoid tumor that usually occurs on the fingers and toes of middle-aged adults. We report on the typical case of a 50-year-old woman with a SAFM in the right big toenail that had been slowly growing for more than 10 years. To our knowledge, this case is the first reported case for which clinical pictures are available. Histologically, the lesion was non-encapsulated and was composed of stellate and spindle cells, arranged in a myxoid matrix. No atypia or mitotic figures were found. Neoplastic cells showed positive staining for CD34 and negative staining for epithelial membrane antigen (EMA), actin, desmin, keratins, S100 protein, CD99, and HMB45. Differential diagnosis encompasses benign and malignant myxoid and spindle cells tumors such as myxoid neurofibroma, sclerosing perineurioma, superficial angiomyxoma, and several low-grade myxoid sarcomas.

Eccrine syringofibroadenoma (ESFA) is a rare eccrine tumor. We report the case of a 70-year-old woman who had presented a pincer nail deformity on the toes for 55 years and a left painless subungual tumor for 2 years. Histologic examination revealed branching anastomosing strands of epithelial cells with ductal structures in a fibrovascular stroma. The luminal cells showed positive staining for carcinoembryonic antigen, as in acrosyringeal cells and cells of dermal ducts. To our knowledge, our case is the first with a subungual location. In the context of chronic trauma due to a pincer nail, it may be classified in the reactive subtype recently described.

Human papillomaviruses (HPV), and particulary HPV 16, have been associated with ungual squamous cell carcinoma (USCC). But their role in tumor development remains unclear. In genital carcinoma, where the oncogenic role of HPV is well established, integration of HPV DNA into the host cell genome seems to be important for malignant transformation. To clarify the issue, we have studied the physical state of HPV 16 in 3 cases of in situ USCC by the polymerase chain reaction and by in situ hybridization. HPV DNA was integrated into the human genome in 2 cases and episomal in 1 case. This particular physical state of HPV 16 in USCC, similar to those encountered in anogenital SCC, confirms the probable role of this kind of virus in the pathogenesis of USCC.

Epithelioid sarcoma (ES) is a rare soft tissue neoplasm that usually occurs on the upper extremity of adolescents and young adults. It rarely occurs during childhood. ES is a slowly growing tumor with a high propensity for recurrences and metastases. This neoplasm is likely to be confused with a variety of benign and malignant conditions. Recognition of ES is important. The treatment consists of wide excision. Misdiagnosis can lead to inappropriate treatment and local recurrences or metastases. We report the case of a 5-year-old girl with an ES on the right forefinger.