PRAME immunohistochemistry as an adjunct for evaluating ambiguous melanocytic proliferation

BACKGROUND

The histopathological assessment of diagnostically ambiguous melanocytic proliferation remains one of the biggest challenges in the dermatopathology field. PRAME (Preferentially expressed Antigen in MElanoma) immunostaining has been shown highly specific for distinguishing unequivocal malignant melanocytic proliferation from benign ones. Knowledge on its utility for evaluating ambiguous melanocytic neoplasms remains limited.

METHODS

We retrieved in our institutional database all cases of diagnostically ambiguous melanocytic neoplasms from January 2016 to January 2021. Each case was subclassified into "favor benign" or "favor malignant" neoplasm using all collected data. Immunohistochemical (IHC) expression of PRAME was assessed and correlated with the final subclassification. Using a previously proposed scoring system, diffuse immunopositivity (>75% of tumor cells) was considered positive. Furthermore, for ambiguous melanocytic proliferation occurring on a pre-existing nevus, the staining was considered positive if more than 75% of the morphologically atypical neoplastic cells were labeled, excluding morphologically unambiguous benign nevocytes.

RESULTS

Fifty-five cases of ambiguous melanocytic proliferation were examined. Thirty-one cases were finally subclassified as "favor malignant" neoplasms and 24 as "favor benign" neoplasms. Thirty-one tumors showed immunopositivity for PRAME, representing respectively 8.3% and 93.5% of "favor benign" and "favor malignant" neoplasms. The specificity and sensitivity of PRAME IHC for benign/malignant distinction were respectively 91.7% and 93.5%.

CONCLUSIONS

PRAME IHC shows high sensitivity and specificity for distinguishing malignant challenging melanocytic proliferations from benign ones and could be used as an everyday tool. However, PRAME immunoreactivity should be interpreted cautiously, knowing that rare benign melanocytic neoplasms could show diffuse positivity.

Cutaneous manifestations in patients with coronavirus disease 2019: clinical and histological findings

The clinical spectrum of coronavirus disease 2019 is getting wider with the exponential increase of patients worldwide. Initially described with flu-like symptoms, variable cutaneous manifestations have been reported, with only few histopathological descriptions. Detection of the virus in cutaneous samples has been assessed in very few cases until now, and the causative role of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has not been proven for every type of cutaneous manifestations yet. We aimed to describe histological features of cutaneous eruptions occurring concomitantly to SARS-CoV-2 infection and assess by immunochemistry and in situ hybridization using RNAscope validation techniques the presence of the virus in skin lesions. We retrieved all skin biopsies received in the departments of pathology and dermatopathology, University Hospital of Strasbourg, performed in hospitalized SARS-CoV-2-infected patients presenting concomitant cutaneous manifestations since March 2020. In situ hybridization and immunostaining using a polyclonal SARS nucleocapsid protein antibody were performed on each sample. Skin biopsies from six patients presenting morbilliform eruption concomitant to SARS-CoV-2 infection were available for evaluation. All six samples showed varying degrees of spongiosis, perivascular inflammatory infiltrates of the dermis, and, for some of them, discrete interface dermatitis. In situ hybridization and immunohistochemistry were negative in all cutaneous samples. Morbilliform rash concomitant to SARS-CoV-2 infection is characterized by mild and unspecific histopathological features with no detectable viral RNA and protein and appears then not to be directly caused by the virus. Even if, at least for a few cases, the differential diagnosis with drug hypersensitivity reaction can be difficult, these cutaneous eruptions seem to rather correspond to paraviral rashes.

[Anatomoclinical and immunohistochemical study of 8 cases of dermatomyofibroma]

INTRODUCTION

Dermatomyofibroma (DMF) is a rare, benign tumour that is little-known among clinicians. However, it has typical clinical, histological and immunohistochemical features that distinguish it from other fibrous tumours.

METHOD

We report herein on the clinical, histological and immunohistochemical aspects of eight cases of DMF identified between 2008 and 2019 at the dermatopathology laboratory of Strasbourg.

RESULTS

Five men and three women of average age at diagnosis of 21 years and 9 months (range: 9 to 54 years) were included. Lesions ranged in size from 1 to 11cm. Most cases involved the upper body (6 cases), with one case on the abdomen and one on the side. The lesions presented as a solitary asymptomatic red or reddish brown nodule or plaque that gradually developed. The plaques were hard and caused functional discomfort on movement of the neck. Well-circumscribed spindle cell proliferation was noted in the reticular dermis parallel to the epidermis, without mitotic figures or cytological atypia. The subcutis was infiltrated in 5 cases. Expression of calponin was positive in all cases but one, while that of caldesmon, PS100 and desmin was negative. Expression of smooth muscle actin was positive in 2 cases, and both cases were also positive for stromylesin-3. CD34 was positive in 2 cases.

DISCUSSION

DMF is an extensive tumour capable of attaining large diameters and must be completely excised. The main differential diagnoses of DMF are dermatofibrosarcoma protuberans, dermatofibroma, fibrous hamartoma, myofibromatosis and cheloid. It can be identified based on various factors, whether clinical (young age, extensive lesion), histological (horizontal proliferation in the reticular dermis) or immunohistochemical (positive expression of calponin).

[Clinical heterogeneity of poikilodermatous mycosis fungoides: A retrospective study of 12 cases]

INTRODUCTION

Poikilodermatous mycosis fungoides is a rare and indolent clinical variant of mycosis fungoides (MF). It can be difficult to distinguish from poikilodermatous parapsoriasis, a group of chronical dermatoses that may sometimes progress to MF. We aimed to specify the clinical, histopathological and developmental features of these entities by means of a retrospective study of 12 cases followed in our center.

PATIENTS AND METHODS

We identified cases of poikiloderma for which a diagnosis of MF or parapsoriasis was made by the physician. Photographs and histological slides were reviewed, and a final diagnosis of MF was made if the International Society for Cutaneous Lymphoma criteria for the diagnosis of early MF were fulfilled.

RESULTS

Twelve patients were included, 10 of whom met of the MF criteria. 5 patients had large poikilodermatous patches or thin, well-defined plaques ; 3 patients had the same lesions associated with classical MF lesions ; finally, 4 patients had widespread ill-defined erythematous lesions in a net-like pattern, described as parakeratosis variegata, including 3 MF. 2 patients with well-defined lesions (one associated with classical MF lesions) progressed to the tumoral stage whereas none of the patients with parakeratosis variegata presented such progression. A total of 5 patients had a high skin phototype (IV and V). Two patients had squamous cell carcinoma on poikilodermatous lesions.

DISCUSSION

Our study suggests that poikilodermatous MF covers a heterogeneous clinical spectrum comprising on one hand a presentation of delimited lesions sharing classical MF risk of progression, and on the other, an entity similar to parakeratosis variegata, an entity overlooked in the French nomenclature, which was particularly benign in our small series, raising the question of its affiliation to the MF group. This question merits further investigation in a larger-scale study.

[Extra-nodal NK/T-cell lymphoma, nasal-type, revealed by cutaneous and ocular involvement]

BACKGROUND

Extra-nodal NK/T-cell lymphoma (ENKTL) is a form of highly malignant non-Hodgkin's lymphoma. There are two types: nasal forms primarily affecting the oropharyngeal sphere and so-called nasal-type extra-nasal forms in which primary skin involvement is the most common feature enabling diagnosis. Herein, we report a case of systemic nasal-type ENKTL (ENKTL-NT) that was diagnosed based on skin involvement associated with ocular involvement.

PATIENTS AND METHODS

A 67-year-old female patient, without immunodepression, was admitted to the dermatology department for a worsening inflammatory scaly patch of skin on her right calf. Secondarily, further lesions appeared on her body as well as a generalized macropapular rash and sores. These were associated with fever spikes, as well as ophthalmoplegia and edema, preventing her from opening her right eyelid. Tests for infectious, autoimmune and inflammatory disorders were negative. A cerebro-orbital scan revealed infiltration and contrast enhancement of the right periocular fat without any mass effect or cerebral extension. A positron emission tomography (PET) scan revealed multiple hypermetabolic skin lesions. Histological analyses indicated dermal-hypodermal lymphomatous tumor proliferation, and immunohistochemical analyses revealed lymphocytes expressing NK-cell markers (strong CD56+ expression), cytotoxic markers (granzyme B and TIA-1), and the presence of Epstein Barr virus (EBV) in the tumor cells. The patient was diagnosed with systemic ENKTL-NT. Her condition deteriorated rapidly, with the onset of refractory macrophage activation syndrome leading to death due to multiple organ failure.

DISCUSSION

Skin involvement in ENKTL is non-specific and uncommon, which can delay diagnosis. Treatment is based on polychemotherapy comprising L-asparaginase and possibly consolidation therapy with autologous or allogeneic hematopoietic stem cell transplantation. The prognosis of ENKTL-NT is poor due the more aggressive nature of the disease compared with the nasal forms, with frequent visceral involvement and macrophage activation syndrome. Skin involvement seems to be a poor prognostic factor. Although ocular involvement is documented, its association with skin involvement is rare and mainly secondary to nasal forms of ENKTL. This case of an extra-nasal form of ENKTL-NT with systemic involvement illustrates the difficulty of diagnosis and the poor prognosis of this type of lymphoma.

[Multifocal chalazodermic amyloidosis: The concept of immunoglobulinemic elastopathy]

INTRODUCTION

Impairment of dermal elastic tissue occurs in different entities associated with immunoglobulins or immunoglobulin-derived protein-secreting clonal plasma cell proliferations, such as amyloid elastosis, anetodermic nodular amyloidosis or monoclonal gammopathy-associated cutis laxa. We report a case of cutaneous immunoglobulinemic amyloidosis revealed by a unique chalazodermic presentation and we review elastic tissue impairment in patients with monoclonal gammopathies.

OBSERVATION

A 67-year-old woman consulted for non-infiltrated anetodermic lesions on the upper left quadrant of her abdomen present for ten years. She also had a chalazodermic plaque with abnormal skin wrinkling and laxity in her right axilla. Biopsies revealed deep dermal and subcutaneous amyloid deposits. Immunohistochemistry with lambda light chain was positive. Orcein staining and electron microscopy showed extensive elastolysis. The patient presented no signs of systemic involvement, but a very small amount of monoclonal IgGλ gammopathy was detected during follow-up.

DISCUSSION

This is a unique chalazodermic presentation of immunoglobulinemic amyloidosis that does not fit into a clearly-defined nosological setting. It highlights the complex interactions between immunoglobulin-derived proteins, including light and heavy chains, and elastic tissue components, leading to different types of impairment of the latter. We therefore suggest the unifying concept of immunoglobulinemic elastopathy, underscoring the need to screen for monoclonal gammopathy in patients presenting elastic tissue impairments.

[Clinicopathological study of purpura: Is a skin biopsy necessary for palpable purpura?]

OBJECTIVE

For many physicians, palpable purpura is synonymous with vasculitis. However, a skin biopsy is almost always performed in common clinical practice in order to confirm the diagnosis. The aim of our study was to assess whether palpable purpura is always indicative of an inflammatory infiltrate in a vessel wall.

PATIENTS AND METHODS

Eighty-seven patients were included in this prospective monocentric study, 45 of whom were presenting a palpable purpura. Patients were classified in two categories: "leukocytoclastic vasculitis" or "other diagnosis". The clinical and histopathological features of patients with a palpable purpura were studied.

RESULTS

The mean age of patients presenting a palpable purpura was 69 years. There were 26 men and 19 women. Of the 43 patients biopsied, 37 were included in the vasculitis group. The sensitivity, specificity, positive predictive value and negative predictive value for a diagnosis of vasculitis in patients with palpable purpura were respectively 82, 65, 86 and 58 %. The Odds ratio was 8.48 (95 % CI, 2.52-31.80; P<0.05).

CONCLUSION

Most of the palpable purpuras examined were indeed related to leukocytoclastic vasculitis. In the remaining cases, biopsy did not contribute to the diagnosis since it only showed purpura without vessel wall inflammation. In our opinion, a skin biopsy is thus not essential where the clinical presentation is typical.

[Pseudoxanthoma elasticum-like disease with deficiency of vitamin K-dependent clotting factors and cutis laxa features]

BACKGROUND

Pseudoxanthoma elasticum (PXE)-like syndrome is characterized by the association of PXE and cutis laxa (CL) features with a deficiency of vitamin K-dependent clotting factors. It was first described in 1971 and was identified as a distinct genetic entity in 2007 with analysis of the GGCX (γ-glutamyl carboxylase) gene, which is involved in congenital deficiency in vitamin K-dependent clotting factors. Here we report a new case of this extremely rare syndrome.

PATIENTS AND METHODS

A 23-year-old female patient was seen for the emergence of loose and redundant skin following extensive weight loss. She also presented a deficiency of vitamin K-dependent clotting factors. Physical examination revealed excessive, leathery skin folds in the axillary and neck regions. A skin biopsy revealed polymorphous and fragmented elastic fibers in the reticular dermis. These were mineralized, as was demonstrated by Von Kossa staining. The clinical features of CL associated with the histopathological features of PXE and vitamin K-dependent clotting factor deficiency led us to a diagnosis of PXE-like syndrome. A molecular study of the GGCX gene showed compound heterozygosity.

DISCUSSION

The GGCX gene is usually responsible for PXE-like syndrome. GGCX encodes a γ-glutamyl carboxylase necessary for activation of gla-proteins. Gla-proteins are involved both in coagulation factors in the liver and in the prevention of ectopic mineralization of soft tissues. Uncarboxylated forms of gla-proteins in fibroblast would thus enable mineralization and fragmentation of elastic fibers.

[Desmoplastic trichoepithelioma: a clinicopathological study, including a comparison with morpheiform basal cell carcinoma]

BACKGROUND

Desmoplastic trichoepithelioma (DTE) is an uncommon form of adnexal tumour that was described for the first time as a separate clinicopathological entity in 1976. We carried out a retrospective histopathological study of a large series of cases of DTE in order to better characterise this tumour and compare it with sclerodermiform basal cell carcinoma (BCC), which is in fact the most common as well as the most complex type of differential diagnosis.

PATIENTS AND METHODS

We included in this study all cases of DTE diagnosed between 1979 and 2001 at our dermatopathology laboratory. The clinical features were taken from the patient files. Diagnosis was confirmed by two different examiners and all microscopic elements were reviewed. The same clinical and demographic data were collected for cases of BCC diagnosed over the same period.

RESULTS

We included 68 cases of DTE in 67 patients in our study, of whom 83.5% were women, and the mean age was 42.8 years. Lesions were found primarily on the head (98.5% of cases), mainly on the cheeks (29.2% of cases) and forehead (23.1% of cases). The diagnosis was only made by the clinician in four cases; in 38 cases the diagnosis made was BCC. In all cases, histological examination revealed thin lines of basaloid epithelial cells associated with small keratinising cysts. A common finding was granulomas with foreign bodies and calcifications. In six cases (8.8%), a tumour combining DTE with an intradermal naevus was observed. Mean clinical follow-up of 8 years (1 to 23 years) in 29 patients showed absence of relapse or metastasis. Over the same period, 662 cases of BCC were recorded in 499 patients, 58.9% of whom were women. The mean age was 65.6 years. The principal location was the nose (34% of cases). No cases of associated naevus were recorded.

COMMENTS

DTE is a firm plaque-like lesion, flesh coloured or yellowish, and generally with a depressed centre; it is seen primarily in middle-aged women and occurs principally on the cheeks and forehead. There is a significant association with naevus, a singular feature among adnexal tumours. On average, it is 10 times less common than BCC. The size of our study groups shows for the first time distinguishing features with regard to BCC, for which the age of onset is far higher and predominance among women less marked. Further, the sites are different, with BCC being seen predominantly on the nose while DTE is seen mainly on the cheeks. A suggested clinical diagnosis is thus possible.