Search Results (10)

Cutaneous pseudolymphomas are benign reactive lymphoid proliferations that often mimic cutaneous lymphomas both clinically and histologically. A diverse array of inflammatory, infectious, and drug-induced dermatoses can closely resemble cutaneous T-cell lymphomas (CTCLs), particularly mycosis fungoides (MFs), posing significant diagnostic challenges. These mimickers may show histopathological features such as epidermotropism, dense lymphocytic infiltrates, or even clonality, making accurate differentiation crucial to avoid overtreatment. This review endeavors to comprehensively discuss the clinicopathologic features of the various inflammatory and infectious dermatoses that may simulate CTCL, drawing on illustrative examples across disease categories. By highlighting important comparative features and emphasizing the importance of clinicopathologic correlation, this review outlines practical strategies for distinguishing true lymphoma from its inflammatory mimics. Full article

Granuloma annulare is a non-infectious granulomatous dermatosis with a probable pathogenic mechanism of delayed-type hypersensitivity, in which the dermal histiocytic granulomatous infiltrate is usually accompanied by a lesser component of lymphocytes. Although there are more common clinical and histopathological patterns of presentation, there are less well-known variants that may pose significant diagnostic challenges by mimicking other inflammatory cutaneous processes or even neoplastic conditions. One of the rarest forms of granuloma annulare is the pseudolymphomatous variant, in which the lymphocytic component is not only highly prominent but may, in some cases, partially or completely obscure the histiocytic component itself. This feature, together with the fact that the clinical presentation of this variant is often atypical—frequently lacking the characteristic annular morphology of conventional granuloma annulare—renders the diagnosis particularly challenging. From an immunohistochemical standpoint, the infiltrates described are predominantly composed of T cells, with only a sparse and scattered B-cell component. In this article, we present a case of granuloma annulare with a pseudolymphomatous B-cell component (PAX5⁺, CD79⁺) and minimal T-cell involvement, observed in a 4 mm skin nodule located on the shoulder of a 48-year-old male. This case therefore broadens the concept of pseudolymphomatous granuloma annulare to include infiltrates predominantly composed of B lymphocytes. Full article

This report describes two cases of solitary subcutaneous nodular lymphoid lesions in dogs. Case 1 involved a 6-year-old male Maltese and Case 2 a 5-year-old female Yorkshire Terrier. Both presented with firm, non-ulcerated dorsal subcutaneous nodules and were unresponsive to corticosteroids. Surgical excision was performed for diagnosis. Histopathology and immunohistochemistry revealed distinct patterns. Case 1 exhibited well-formed lymphoid follicles with CD20⁺/PAX5⁺ B cells and strong BCL6 but absent BCL2 expression, consistent with B-cell pseudolymphoma. Case 2 demonstrated diffuse CD3⁺ T-cell infiltrates with adipocyte rimming and minimal BCL2/BCL6 expression, diagnostic for SPTCL. Despite their similar clinical presentation, these two lesions were histopathologically and immunophenotypically distinct. These findings underscore the importance of histologic and immunophenotypic correlation in accurately distinguishing benign from malignant subcutaneous lymphoid proliferations in dogs. Full article

The Wolf isotopic response (WIR) refers to the development of cutaneous lesions in areas of previously healed but unrelated skin disease. While most are observed in healed herpes zoster, WIR has been reported in various other contexts. Affected areas are believed to exhibit immune dysregulation, lymphatic dysfunction, and altered neuromediator activity, increasing susceptibility to inflammatory, neoplastic, and infectious conditions. This phenomenon aligns with the broader concept of the “immunocompromised district”, which also encompasses the Koebner phenomenon and its reverse. Herein, we present the case of a 96-year-old woman who developed multiple cysts and comedones at the site of a resolved herpes zoster. Due to persistent and refractory inflammation, curettage was performed, and histopathological examination revealed angiosarcoma with a pseudolymphomatous reaction interspersed among the cysts. The coexistence of multiple types of WIR is rare but not unprecedented, highlighting the importance of recognizing the diverse pathologic conditions that can arise in such settings. In this review, we explore the historical evolution of terminology used to describe lesions in vulnerable skin areas and related phenomena. We also provide an updated overview of current pathogenic theories and present a comprehensive compilation of postherpetic reactions reported to date. Full article

Acrodermatitis chronica atrophicans (ACA) is not an infrequent condition in Europe. However, the characteristic skin lesions are often confused by non-dermatologists with other conditions. We report three unusual cases in which we made a definitive diagnosis of ACA complicated by cutaneous marginal zone lymphoma, juxta-articular fibrotic nodules, or bilateral sensory polyneuropathy. In all cases, correct diagnosis and adequate treatment was delayed over a period of at least 12 months. We initiated systemic antibiotics resulting in full recovery in these patients. The present case reports underscore that ACA may be associated with unusual clinical presentation which potentially result in delay of correct diagnosis and treatment. Hence, ACA diagnosis may be considerably delayed leading to inappropriate therapy exposure, prolonged patients’ suffering, and causing unnecessary cost. Thus, physicians who are not familiar with skin conditions should seek a timely dermatologist consultation. Full article

While ex vivo confocal laser scanning microscopy has previously demonstrated its utility in most common skin diseases, its use in the assessment of dermatological entities with lower incidence remains unexplored in most cases. We therefore aimed to evaluate the diagnostic efficacy of some rare skin tumors as well as a few inflammatory skin diseases, that have not yet been studied in ex vivo confocal laser scanning microscopy. A total of 50 tissue samples comprising 10 healthy controls, 10 basal cell carcinoma, 10 squamous cell carcinoma, and 20 rare skin conditions were imaged using the newest generation ex vivo confocal microscopy (Vivascope 2500 M-G4, Vivascope GmbH, Munich, Germany). Three blinded investigators were asked to identify characteristic features of rare skin disorders and distinguish them from more common skin diseases in the ex vivo confocal microscopy images. Our findings present the capability of ex vivo confocal microscopy to display distinctive morphologic patterns in common and rare skin diseases. As might be expected, we found a strong correlation between imaging experience and diagnostic accuracy. While the imaging inexperienced dermatohistopathologist reached 60% concordance, the imaging-trained dermatologist obtained 88% agreement with dermatohistopathology. The imaging-trained dermatohistopathologist achieved concordance up to 92% with gold-standard dermatohistopathology. This study highlights the potential of ex vivo confocal laser scanning microscopy as a promising adjunct to conventional dermatohistopathology for the early and precise identification of rare dermatological disorders. Full article

Topical photodynamic therapy (PDT) is a non-invasive treatment modality frequently used in dermatology to treat superficial skin cancers but also some inflammatory or infectious dermatoses. PDT appears a more and more promising therapeutic option also for cutaneous lymphomas, either of T- or B-cell origin. It is a well-tolerated treatment and has excellent cosmetic outcomes, less side effects compared to other therapies (steroids, surgery, radiotherapy, and so on), no particular contraindications, and is easily repeatable in case of relapses. However, how PDT works in the treatment of cutaneous lymphoproliferative diseases is poorly understood and the literature data are still controversial. Further randomized, controlled clinical trials involving a greater number of patients and centers with a long follow-up are necessary to assess the efficacy of PDT and establish a unique standardized treatment protocol in relation to the lymphomatous disease and the type, thickness, and location of the lesions. Full article

Background: Primary cutaneous follicular B-cell lymphoma (PCFBCL) represents an indolent subtype of Non-Hodgkin’s lymphomas, being clinically characterized by slowly growing tumors of the skin and common cutaneous relapses, while only exhibiting a low propensity for systemic dissemination or fatal outcome. Up to now, only few studies have investigated underlying molecular alterations of PCFBCL with respect to somatic mutations. Objectives: Our aim was to gain deeper insight into the pathogenesis of PCFBCL and to delineate discriminatory molecular features of this lymphoma subtype. Methods: We performed hybridization-based panel sequencing of 40 lymphoma-associated genes of 10 cases of well-characterized PCFBCL. In addition, we included two further ambiguous cases of atypical B-cell-rich lymphoid infiltrate/B-cell lymphoma of the skin for which definite subtype attribution had not been possible by routine investigations. Results: In 10 out of 12 analyzed cases, we identified genetic alterations within 15 of the selected 40 target genes. The most frequently detected alterations in PCFBCL affected the TNFRSF14, CREBBP, STAT6 and TP53 genes. Our analysis unrevealed novel mutations of the BCL2 gene in PCFBCL. All patients exhibited an indolent clinical course. Both the included arbitrary cases of atypical B-cell-rich cutaneous infiltrates showed somatic mutations within the FAS gene. As these mutations have previously been designated as subtype-specific recurrent alterations in primary cutaneous marginal zone lymphoma (PCMZL), we finally favored the diagnosis of PCMZL in these two cases based on these molecular findings. Conclusions: To conclude, our molecular data support that PCFBCL shows distinct somatic mutations which may aid to differentiate PCFBCL from pseudo-lymphoma as well as from other indolent and aggressive cutaneous B-cell lymphomas. While the detected genetic alterations of PCFBCL did not turn out to harbor any prognostic value in our cohort, our molecular data may add adjunctive discriminatory features for diagnostic purposes on a molecular level. Full article

The term “pseudomalignancy” covers a large, heterogenous group of diseases characterized by a benign cellular proliferation, hyperplasia, or infiltrate that resembles a true malignancy clinically or histologically. Here, we (i) provide a non-exhaustive review of several inflammatory skin diseases and benign skin proliferations that can mimic a malignant neoplasm in children, (ii) give pathologists some helpful clues to guide their diagnosis, and (iii) highlight pitfalls to be avoided. The observation of clinical–pathological correlations is often important in this situation and can sometimes be the only means (along with careful monitoring of the disease’s clinical course) of reaching a firm diagnosis. Full article

Nodular lymphoid hyperplasia (NLH) belongs to a very rare, mild, lymphoproliferative disease of unestablished aetiology historically included in the group of pseudolymphomas. Its existence was controversial for many years, until modern techniques of pathomorphological diagnosis approved it as a separate entity of lung disease. It manifests in the form of well limited nodules localized in the lungs, which are mostly identified accidentally. Clinical symptoms are rare and nonspecific; the disease usually occupies only one lung. Pathomorphological diagnosis requires immunohistochemical designation of expressions of numerous antigens in order to exclude malignant lymphoma of the lungs. Surgical resection is used in cases of larger nodules; the smaller ones require periodic observation, and the prognosis is good. The authors describe the case of 65-year-old woman with pulmonary nodules which were detected accidentally in the right lung. The patient was qualified for right-sided videothoracoscopy and removal of the lung nodule. In classic HE staining of the histological material, the presence of lymphoid infiltration of the lungs was revealed, which formed lymph follicles with reactive germinal centres. In order to differentiate from the malignant lymphatic expansion, immunohistochemical designations were made, which showed positive expression of CD20 antigen in the B cell zone, positive expression of the CD3 antigen in the T cells zone, positive expression of CD23 antigen in the lymph follicles, negative expression of bcl-2 in the lymph follicles, and positive expression of MIB-1 in the germinal centres of lymph follicles. Such a histopathological and immunohistochemical picture provided the basis for diagnosis of nodular lymphoid hyperplasia of the lung. Full article