Histological predictors of outcome for cutaneous squamous cell carcinoma in renal transplant patients: A case-control study.

Background: Cutaneous squamous cell carcinoma is a significant cause of morbidity for immunosuppressed patients such as organ transplant recipients; however, histological parameters which predict the likelihood of tumor progression are typically based on general population studies in which immunosuppressed patients represent only a small fraction of cases. Objectives: To determine the histological parameters which have independent prognostic value for cutaneous squamous cell carcinoma arising in renal transplant recipients. Methods: Case-control study incorporating a retrospective blinded histological review of 70 archived specimens of cutaneous squamous cell carcinoma diagnosed in renal transplant recipients, comprising 10 cases where the tumor had progressed and 60 controls. Results: Progression was significantly associated with head and neck location, size, depth, poor histological grade, perineural invasion (including small caliber perineural invasion), lymphovascular invasion, and a desmoplastic growth pattern. Limitations: The retrospective nature and the low number of cases compared to controls. Conclusion: In immunosuppressed patients both small caliber perineural invasion and a desmoplastic growth pattern may also have prognostic significance in addition to other histological parameters already recognized in formal staging schemes.

Bowen disease is not synonymous with intraepidermal squamous cell carcinoma.

The terms 'Bowen disease' and 'intraepidermal squamous cell carcinoma' are sometimes considered synonymous. In this paper we present historical, clinical, histological and molecular evidence that this is incorrect. The term Bowen disease should be reserved for a subset of intraepidermal squamous cell carcinoma with a distinctive and reproducible morphological pattern, described in detail by Bowen in 1912. One other common subset of intraepidermal squamous cell carcinoma represents progression of actinic keratosis. In some cases the separation of these two common patterns of intraepidermal squamous cell carcinoma can be challenging and there are patterns of intraepidermal squamous cell carcinoma which appear to represent other distinct pathways. However, there is emerging biological evidence to support this distinction and reason to suspect that the types of invasive squamous cell carcinoma which arise from these different pathways may show important clinical and biological differences, particularly in the era of targeted and immunomodulatory therapy for advanced disease.

NUT Expression Is of Diagnostic Utility in the Distinction of Digital Papillary Carcinoma From Poroid Hidradenoma.

ABSTRACT: The distinction between digital papillary adenocarcinoma (DPAC) and benign cutaneous adnexal tumors is clinically important and can be challenging. Poroid hidradenoma frequently occurs at acral sites and can show a number of histological features, which overlap with digital papillary adenocarcinoma. Recent work has shown that YAP1-NUTM1 fusions are frequent in poroid hidradenoma and are associated with nuclear protein in testis (NUT) expression by immunohistochemistry. We evaluated the expression of NUT-1 by immunohistochemistry in 4 cases of DPAC and 4 cases of poroid hidradenoma. Three of 4 cases of poroid hidradenoma showed strong NUT-1 expression, with no staining in any of the cases of DPAC. These results suggest that NUT-1 immunohistochemistry may be a useful additional tool in evaluating this differential diagnosis.

Expression of Melan-A in cutaneous granular cell tumours: a diagnostic pitfall.

Morphological overlap exists between cutaneous granular cell tumours (GCT) and malignant melanoma, with the melanocyte-specific markers HMB45 and Melan-A commonly used to support the diagnosis of melanoma. We recently encountered several cases of GCT in our practice showing strong expression of Melan-A. The aim of this study was to establish the prevalence of positive immunohistochemical staining for Melan-A and HMB45 in a series of unequivocal GCTs. We also aimed to assess the prevalence of staining for PRAME (PReferentially expressed Antigen in MElanoma), a marker expressed in >80% of primary melanomas as well as many non-melanocytic tumours. A total of 20 cutaneous/subcutaneous GCTs were evaluated using Melan-A, HMB45 and PRAME immunohistochemistry. Staining for Melan-A and HMB45 was scored using a semiquantitative scale from 0 (absent) to 3+ (staining present in >50% of tumour cells). PRAME expression was recorded as either positive (>75% of cell nuclei staining) or negative. Melan-A expression was observed in four GCTs (20%), with strong and diffuse (3+) staining seen in two cases (10%), both from anogenital areas. Weak patchy nuclear PRAME expression was seen in every case, interpreted to be negative. HMB45 was also negative in all cases (100%). Our study demonstrates that Melan-A expression can be strong and diffuse in a subset of otherwise unequivocal cutaneous GCTs, which may cause diagnostic confusion with malignant melanoma. HMB45 and PRAME did not stain any of the GCTs in our series.

Skin Biopsy in Pediatric Oncology/Hematopoietic Stem Cell Transplantation Patients.

ABSTRACT: The aim of this study was to review the dermatopathological findings in skin biopsy specimens from pediatric oncology and hematopoietic stem cell transplantation patients over a 20-year period. Three hundred fifty-two skin biopsies from 240 patients were reviewed, and the findings were grouped into 6 categories: index neoplasms, nonindex neoplasms, infections, graft-versus-host disease, other treatment complications, and others. Among the index neoplasms identified on skin biopsy, the most common conditions were Langerhans cell histiocytosis (14 patients) and melanoma (7 patients), with other hematological malignancies and an array of soft-tissue tumors accounting for the bulk of the remainder. Neoplastic conditions common in general dermatopathological practice such as basal cell carcinoma and squamous cell carcinoma were uncommon, each being identified in only 1 patient younger than the age of 18, although basal cell carcinomas developing subsequently in young adult life were identified in 7 patients. Infections were common, with infectious agents or viral cytopathic effects (not including human papillomavirus) identified in 34 biopsies. A significant proportion (74%) represented invasive fungal infections, which are of very significant clinical importance. Biopsies performed for a clinical suspicion of graft-versus-host seldom showed histological features to suggest an alternative diagnosis, with only a single case suggesting a diagnosis of toxic erythema of chemotherapy identified.

An Atypical Deep Penetrating Nevus With Mutations in Beta Catenin , BRAFV600E , and IDH1R132C in an 8-Year-Old Boy.

ABSTRACT: Deep penetrating nevus (DPN) is a pigmented melanocytic tumor which typically displays a wedge-shaped deep penetrating architecture. Some cases show a coexisting component resembling conventional melanocytic nevus. These morphological attributes are correlated with the acquisition of genomic alterations in the Wnt pathway on a background of underlying activating MAPK pathway mutations. Lesions with features of DPN, but displaying expansile architecture, sheet-like arrangement of cells, cytological atypia, and/or more than rare mitotic activity have been described as "atypical deep penetrating nevus" or "deep penetrating melanocytoma." The molecular correlates of these atypical morphological features are not well-established. In this case report, we describe a tumor in an 8-year-old boy with histological features of atypical DPN showing somatic BRAFV600E , beta catenin , and IDH1R132C mutations. The combination of abnormalities in MAPK and Wnt pathways with IDH1 mutations seems to be a reproducible feature in a subset of atypical DPNs. Whether this "three-hit" combination is associated with a significant risk of adverse outcome remains to be established.

Correlation of FISH and PRAME Immunohistochemistry in Ambiguous Superficial Cutaneous Melanocytic Proliferations.

ABSTRACT: Preferentially expressed antigen in melanoma (PRAME) is a tumor-associated repressor of retinoic acid signaling which is expressed in melanoma and has emerged as a potential biomarker for malignant behavior in melanocytic neoplasms. Although ancillary molecular techniques such as fluorescence in situ hybridization (FISH) are established techniques in the diagnosis of problematic cutaneous melanocytic proliferations, they are expensive, time-consuming, and require appropriate infrastructure, which places them out of reach of some laboratories. The advent of readily available commercial antibodies to PRAME has the potential to provide a more accessible alternative. The aim of this study was to determine whether immunohistochemistry for PRAME could serve as a surrogate for FISH analysis in a subgroup of challenging superficial melanocytic proliferations. Cases which had previously been submitted for FISH analysis were stained for PRAME and interpreted by a panel of at least 3 dermatopathologists is a blinded fashion. Of a study set of 55 cases, 42 (76%) showed a pattern of PRAME immunostaining which was concordant with the cytogenetic interpretation, with an unweighted kappa of 0.42 (representing mild-to-moderate agreement). Thus, although there was a correlation between positive immunohistochemistry for PRAME and abnormal findings on FISH analysis, in our view, the concordance was not sufficient to enable PRAME immunohistochemistry to act as a surrogate for FISH testing. Our findings reiterate the principle that interpretation of problematic superficial melanocytic proliferations requires a synthesis of all the available data, including clinical scenario, morphological features, immunohistochemistry, and ancillary molecular investigations.

Large nested melanoma: a clinicopathological, morphometric and cytogenetic study of 12 cases.

A group of melanomas characterised by predominant growth as large nests within the epidermis has been described. These cases present a diagnostic challenge, as many traditional architectural criteria for the recognition of melanoma are absent. We report the clinical, histological, immunohistochemical, morphometric and cytogenetic features of a series of 12 cases of large nested melanoma. In this series, large nested melanoma accounted for 0.2% of cases of melanoma. The majority occurred on the trunk of middle aged patients with absent or minimal solar elastosis and 42% were associated with a component of benign intradermal melanocytic naevus, speaking to classification of these melanomas as falling within the spectrum of lesions developing in skin with low cumulative sun damage. In 67% of cases invasive melanoma was present. Criteria such as asymmetry, variation in nest size and intraepidermal nests with an underlying rim of junctional keratinocytes appear to be highly specific, and are strongly predictive of typical cytogenetic abnormalities of melanoma, which were identified in 92% of cases. Conversely, in addition to features which are definitionally absent or limited, features such as solar elastosis and cytological atypia do not appear to be particularly helpful in recognition of this variant.

Histiocytoid Melanoma.

While most melanomas display well-characterised and readily recognised architectural and cytomorphological features, unusual variants can create diagnostic difficulties. Variants which mimic benign or reactive processes are particularly problematic. We report 5 cases of melanoma characterised by a subtle microscopic appearance reminiscent of a benign dermal histiocytic infiltrate, which we refer to as "histiocytoid melanoma." These lesions are characterised clinically by ill-defined areas of cutaneous pigmentation, which in several cases reached large proportions. Microscopically, there is a subtle interstitial pattern of infiltration by predominantly single cells with a histiocytoid morphology, often resembling melanophages. Immunohistochemical confirmation was typically required, with the cells showing positive labelling for Sox-10 as well as Melan-A. In several examples, the proliferation extended to clinically uninvolved surgical margins, necessitating multiple excisions, and many of our patients have experienced locoregional recurrence. However, none have developed distant metastases or died of melanoma. While uncommon, this subtle variant is important to recognise in order to ensure adequate histological clearance is obtained.

Histological Features of Flagellate Erythema.

Flagellate erythema is a distinctive eruption characterized by "whip-like" linear or curvilinear streaks and plaques, occurring mainly on the trunk. It has classically been described in 2 disparate clinical settings: chemotherapy with bleomycin and ingestion of mushrooms (most commonly Shiitake mushrooms). Most of the literature comprises single case reports, often with minimal histological description of rather nonspecific features. We describe in detail the histological features of 3 cases of flagellate erythema (2 related to bleomycin therapy and one related to ingestion of mushrooms) and review the findings described in the literature to define the spectrum of histological changes encountered in this eruption. Our 3 cases showed mild epidermal changes, with spongiosis and variable interface inflammation. All 3 showed a relatively prominent dermal lymphohistiocytic infiltrate, with features suggestive of a lymphocytic vasculopathy extending to at least the mid-reticular dermis. Eosinophils were a prominent component of the inflammatory infiltrate in 2 cases. Our review of the literature identified a total of 45 publications, representing reports of 46 patients, containing histological information. As well as bleomycin- and mushroom-related cases, similar eruptions have been reported in the context of connective tissue disease and other drugs. Although cases related to connective tissue disease show features of the underlying condition, cases secondary to drugs or mushrooms predominantly show features compatible with common patterns of exanthematous/morbilliform drug reaction. In particular, subtle spongiosis and/or interface dermatitis combined with a dermal lymphocytic infiltrate that includes increased numbers of eosinophils is a common finding. Features of a lymphocytic vasculopathy may be seen in a subset of these cases.

A Practical Approach to the Diagnosis of Melanocytic Lesions.

CONTEXT.­: Melanocytic lesions are common in routine surgical pathology. Although the majority of these lesions can be confidently diagnosed using well-established morphologic criteria, there is a significant subset of lesions that can be diagnostically difficult. These can be a source of anxiety for patients, clinicians, and pathologists, and the potential consequences of a missed diagnosis of melanoma are serious. OBJECTIVE.­: To provide a practical approach to the diagnosis of melanocytic lesions, including classic problem areas as well as suggestions for common challenges and appropriate incorporation of ancillary molecular techniques. DATA SOURCES.­: Literature search using PubMed and Google Scholar, incorporating numerous search terms relevant to the particular section, combined with contemporaneous texts and lessons from personal experience. CONCLUSIONS.­: Although a subset of melanocytic lesions can be diagnostically challenging, the combination of a methodical approach to histologic assessment, knowledge of potential diagnostic pitfalls, opinions from trusted colleagues, and judicious use of ancillary techniques can help the pathologist navigate this difficult area.

Unusual Case of Combined Gliomeningeal Heterotopia on the Nose of an Infant.

Nasal glial heterotopia ("nasal glioma") and cutaneous heterotopic meningeal nodules ("primary cutaneous meningioma") are rare congenital lesions characterized by the presence of heterotopic mature cerebral tissues. Nasal glial heterotopia occurs predominantly in the nasal area and typically does not contain meningothelial elements, whereas heterotopic meningeal nodules occur predominantly on the scalp and do not contain glial elements. In this article, we report an unusual case of cutaneous heterotopia on the nose of an infant composed of both glial and meningothelial elements. The glial component was characterized by irregular islands of predominantly astrocytic cells, on a fibrillary background. The meningothelial component was characterized by bland ovoid cells with focal intranuclear inclusions forming whorled arrangements, with associated psammomatous calcification. To our knowledge, this is the first time such a lesion has been documented. It has also provided us with an opportunity to review the literature regarding heterotopic deposits of both glial and meningothelial tissues.

Giant proliferating pilomatricoma; report of a rare entity.

Proliferating pilomatricoma is a benign tumour and a rare variant of pilomatricoma that has the potential for local recurrence if incompletely excised. We report a case of giant proliferating pilomatricoma on the forearm of a 66-year-old woman. This tumour was unusually large and the presence of ulceration and rapid growth raised clinical suspicion of malignancy. The identification of shadow or ghost cells is a good clue to matrical differentiation, which can be confirmed by ß-catenin immunostaining.

Paediatric cutaneous adnexal tumours: a study of 559 cases.

Cutaneous adnexal tumours encompass a wide group of lesions with apocrine, eccrine, follicular, sebaceous and mixed differentiation. The large majority are benign and represent sporadic lesions, though malignant forms are occasionally encountered and some cases develop in the setting of inherited tumour syndromes. Accurate histological classification can be difficult as there are numerous histological appearances, many of which are individually uncommon, and complex, overlapping and historically variable nomenclature is typical. The aim of this study was to review and classify the spectrum of cutaneous adnexal tumours seen in patients 18 years of age and under in two major tertiary centres over a 20 year period. A total of 559 cases were included, with 60% occurring in female patients. The large majority (87%) occurred in the head and neck region and were benign. Only one (0.2%) was malignant. The original diagnosis was supported by histological review in 99% of cases of pilomatricoma reviewed, but in only 71% of non-pilomatricoma cases reviewed. The most common lineage was follicular (97%), with pilomatricoma accounting for the large majority of lesions. Predominant glandular/ductal differentiation was seen in 3% of cases, with no tumours showing predominant sebaceous differentiation.

The "Umbrella Sign": A Useful Clue in the Diagnosis of Melanocytic Lesions in Sun Damaged Skin.

As ultraviolet radiation is an important aetiological agent in melanoma development, the presence of solar elastosis is an important factor in the assessment of any melanocytic lesion. However, melanocytic naevi are also seen in chronically sun damaged skin, particularly in regions with high levels of ultraviolet exposure and fair skinned populations. It has previously been noted that the relationship of a melanocytic proliferation to elastic fibers in the dermis can be of discriminatory value in the separation of melanoma from melanocytic naevus, in particular, it has been proposed that naevi act as a "sunscreen," which may result in a histological clue that the authors colloquially refer to in practice as "the umbrella sign." The aim of this study was to evaluate the patterns of solar elastosis within and beneath melanocytic proliferations developing in sun damaged skin and to determine the utility of the "umbrella sign" in diagnostic practice. We assessed 81 melanocytic proliferations in sun damaged skin for the presence of an umbrella sign, that was present in 49/53 melanocytic naevi (92%) compared with only 2/28 melanomas (7%, P < 0.05). In addition, entrapped elastotic fibers displaying distinct purple discolouration were identified in 16 melanocytic naevi. This finding was not identified in any of the melanomas. The umbrella sign appears to be a useful clue in the distinction of melanoma from melanocytic naevus in sun damaged skin, although as with all histological features in melanocytic pathology, it requires interpretation within a multifactorial assessment cognizant of potential diagnostic pitfalls.