Unveiling the Rarity: CD20 Expression in Mycosis Fungoides and Its Clinical Significance.

ABSTRACT: Although CD20 expression is typically scarce in mycosis fungoides (MF), it is more commonly associated with T-cell lymphomas. Nevertheless, isolated instances of CD20-positive MF have been documented infrequently. Here, we present a unique case of CD20-positive MF in a 30-year-old man who manifested with a hypopigmented patch on the anterior chest. Histopathological examination revealed epidermotropic infiltrates of small- to medium-sized lymphocytes with hyperchromatic and cerebriform nuclei aligned along the basal and low-mid layers of the epidermis. Immunophenotypic analysis demonstrated neoplastic T cells expressing CD4+, CD8+, and CD3+ with the loss of CD7. Intriguingly, a notable subset of the neoplastic T cells exhibited CD20 expression. This case contributes to the sparse literature on CD20-positive MF and underscores its diagnostic and clinical ramifications. The role of B cells has been more thoroughly characterized in T-cell lymphomas other than MF. However, its significance in MF remains unclear due to the scarcity of reported cases. Some hypotheses propose that the B cells' expression might indicate immune dysregulation or complex interactions within the tumor microenvironment. Another perspective suggests it could signify a progression of the disease towards a more aggressive lymphoma phenotype. Further investigation and documentation of similar cases is imperative to elucidate the clinical features, prognosis, and optimal therapeutic strategies. The long-term prognosis and outcomes in patients with hypopigmented MF and CD20 positivity remain ambiguous, underscoring the necessity for continued research and scrutiny of analogous cases.

Navigating Diagnostic and Therapeutic Challenges in Primary Cutaneous Gamma/Delta T-Cell Lymphoma: A Case Study of Fatal Outcomes Within Two Months.

ABSTRACT: Primary cutaneous gamma/delta T-cell lymphoma (PCGD-TCL) is a rare yet highly aggressive subtype of primary cutaneous lymphoma. Characterized by its challenging diagnosis and poor prognosis, PCGD-TCL presents unique clinical and histopathological features that distinguish it from other primary cutaneous lymphoma subtypes. Here, we report the case of a 75-year-old man who initially presented with multiple erythematous indurated plaques over his back and bilateral lower extremities. The initial biopsy suggested primary cutaneous T-cell lymphoma (PCTCL) with a CD30-negative phenotype. However, within a 2-month interval, the disease progressed rapidly, manifesting as extensive skin involvement across the chest and upper extremities. A repeat skin biopsy was performed, revealing dermal atypical lymphocytes without epidermotropism. Immunohistochemical analysis demonstrated positivity for CD3, CD5, and CD4, as well as T-cell receptor delta (TCR delta) expression, along with the loss of CD8 and CD30 expression. These findings were consistent with a diagnosis of PCGD-TCL. Despite therapeutic interventions, including systemic treatments, the patient's condition deteriorated rapidly, ultimately leading to his demise within a month of receiving the PCGD-TCL diagnosis. This case highlights the diagnostic complexities associated with PCGD-TCL, emphasizing the importance of careful histopathological examination and immunophenotypic characterization. Given its aggressive nature and propensity for rapid dissemination, early recognition of PCGD-TCL is paramount for initiating appropriate therapeutic interventions. However, effective treatment options for PCGD-TCL remain limited, and the disease typically carries an unfavorable prognosis. Further research is needed to elucidate the underlying molecular mechanisms driving the pathogenesis of PCGD-TCL, to identify novel therapeutic targets, and to improve patient outcomes. In addition, increased awareness among clinicians and pathologists regarding the clinical presentation and diagnostic criteria of PCGD-TCL is crucial for facilitating timely diagnosis and management of this challenging malignancy.

High-Grade Spindle Cell Sarcoma of the Scalp With an MGA::NUTM1 Gene Fusion in a Pediatric Patient.

ABSTRACT: NUT carcinoma (NC) is a rare and aggressive neoplasm associated with a poor prognosis. NC is characterized by a NUTM1- rearrangement on chromosome 15q14, commonly fused with the BRD4 or BRD3 gene . A rare subset of NC defined by fusion of NUTM1 with the MGA gene has been identified, showing mesenchymal differentiation on histology. Few cases of spindle cell sarcomas harboring MGA::NUTM1 gene fusions have been reported in the literature. We describe a case of spindle cell sarcoma harboring an MGA::NUTM1 fusion in a 6-year-old male patient. In contrast to typical cases of spindle cell carcinomas or NC, NUTM1 fusion-positive sarcomas are associated with a better prognosis. This report highlights the importance of diagnostic workup of undifferentiated neoplasms, as identification of the MGA::NUTM1 fusion in spindle cell sarcoma could be used in treatment algorithms and lead to better outcomes, to the benefit of patients.

Lymphangitic Melanomatosis: Case Report of Intralymphatic Spread of Melanoma in a 66-year-old Man.

ABSTRACT: Melanoma with lymphatic invasion has been associated with increased risk of metastasis, but the mechanisms and clinical implications are poorly understood. Although current reports have documented angiotropic spread of melanoma and suggest lymphatic spread of melanoma to increase the likelihood of metastasis, to our knowledge, lymphangitic metastatic melanoma resembling cutaneous carcinomatosis or presenting with facial hyperpigmentation has not been described. In this case report, we describe extensive cutaneous intralymphatic spread of melanoma, or lymphangitic melanomatosis, producing macular skin pigmentation in a 66-year-old man.

Cutaneous Syncytial Myoepithelioma: An Uncommon and Distinct Variant of Cutaneous Epithelioid Neoplasm.

BACKGROUND: Cutaneous syncytial myoepithelioma (CSM) is an uncommon and distinct variant of cutaneous myoepithelioma. We aim to present a case of CSM to enhance the recognition of this unique variant, encompassing its clinical characteristics, histopathological features, immunohistochemical staining, and therapeutic approaches. CASE PRESENTATION: A 10-year-old girl presented with a dome-shaped nodule located on the skin of her left medial distal arm. Microscopic examination of the skin biopsy revealed a well-defined dermal nodular lesion, surrounded by an epidermal collarette. Tumor cells were composed of epithelioid to spindle-shaped cells with round-to-oval nuclei, small nucleoli, and abundant eosinophilic cytoplasm with a syncytial-like growth pattern. A moderate degree of nuclear pleomorphism was noted. Mitotic activity was not prominent. Immunohistochemical staining revealed positive staining for epithelial membrane antigen, GLUT1, collagen IV, and S100. Smooth muscle actin, CD10, and CD68 showed patchy positivity. CD31, CD34, p63, SOX10, anaplastic lymphoma kinase (ALK), glial fibrillary acidic protein, pankeratin (AE1/AE3/PCK26), Melan-A, and CD1a were negative. Fluorescence in situ hybridization targeting TFE3 and ALK genes was negative. The differential diagnosis included ALK-negative epithelioid cell histiocytoma, epithelioid perineurioma, and CSM. Based on the above findings, a diagnosis of CSM was rendered. DISCUSSION: CSM is a benign cutaneous neoplasm composed of sheets of histiocytoid or short spindle cells with pale eosinophilic cytoplasm with a syncytial-like growth pattern. Clinically, CSM often presents as a painless, slow-growing nodule or plaque in a broad anatomical distribution with a preference for the distal extremities. CSM is characteristically positive for epithelial membrane antigen (EMA) and S100 protein and negative for keratins. In challenging cases, molecular testing for EWSR1 gene rearrangement and EWSR1-PBX3 gene fusion aid in confirming the diagnosis. CONCLUSIONS: The histologic features of CSM present a unique set of challenges posing a diagnostic dilemma, as they can bear resemblance to a range of benign and malignant cutaneous neoplasms including ALK-negative epithelioid cell histiocytoma, epithelioid perineurioma, malignant or nevoid melanoma, and epithelioid sarcoma. An accurate diagnosis is crucial for guiding proper clinical management considering that this entity typically demonstrates an excellent prognosis following a complete surgical excision.

Muir-Torre syndrome and recent updates on screening guidelines: The link between colorectal tumors and sebaceous adenomas in unusual locations.

BACKGROUND: Muir-Torre syndrome (MTS) is a rare genetic disorder that is caused by mismatch repair (MMR) protein mutations. MTS increases the risk of developing skin and gastrointestinal tumors such as sebaceous adenomas (SAs), sebaceous carcinomas, colorectal cancer, endometrial cancer, and ovarian cancer. The risk of developing these types of tumors varies depending on the involved mutation and the individual's family history risk. CASE PRESENTATION: A 47-year-old male presented with multiple skin lesions on the scalp, face, flank, and back. The examination revealed well-circumscribed, dome-shaped papules with a yellowish appearance with white oily material in the center. Histopathologic examination showed a well-circumscribed sebaceous neoplasm consistent with a mixture of basaloid cells and lobules of bland-appearing mature adipocytes that communicate directly to the surface epithelium. Focal cystic changes and peritumoral lymphocytic infiltrate were noted. Increased mitotic figures were seen in the basaloid cell component. The overall findings were consistent with the diagnosis of SAs. MMR staining showed preserved expression in MLH1 and PMS2 proteins, while MSH2 and MSH6 staining showed loss of protein expression. A screening colonoscopy showed numerous colon and rectal tumors, prompting concerns about the likelihood of MTS. Surgical intervention was pursued for complete resection. Histology revealed a diagnosis of mucinous adenocarcinoma/adenocarcinoma with mucinous features of the colon. The diagnosis of MTS was supported by molecular testing that revealed MSH2 germline mutation. The increased likelihood of MTS was attributed to the occurrence of SAs in unusual locations of the head and neck regions, unlike typical cases. CONCLUSION: MTS is a rare clinical condition that necessitates prompt thorough evaluation and periodic surveillance. When SA is encountered in atypical locations, it is important to consider additional testing supported by immunohistochemical staining, molecular testing, and regular screening to exclude the likelihood of MTS.

Mohs micrographic surgery and dermatopathology concordance: An analysis of 1421 Mohs cases over 17 years.

BACKGROUND: The success of Mohs micrographic surgery depends on the surgeon's ability to correctly interpret intraoperative frozen sections. OBJECTIVE: This retrospective study analyzed the rate of concordance between Mohs surgeons and dermatopathologists in reading slides from Mohs surgery cases. METHODS: A dermatopathologist reviewed all the frozen sections and the corresponding Mohs map for every 30th Mohs case at a practice employing 6 different Mohs surgeons during 2001-2017. Cases in which the dermatopathologist and the Mohs surgeon disagreed on the interpretation were noted. RESULTS: The concordance rate between Mohs surgeons and dermatopathologists was 99.79%. The 3 discordant cases included a case of squamous cell carcinoma, a case of superficial basal cell carcinoma, and a case of hypertrophic squamous cell carcinoma in situ. LIMITATIONS: This analysis is limited to fellowship-trained Mohs surgeons and, therefore, might not be applicable to all physicians who perform Mohs. CONCLUSION: Fellowship-trained Mohs surgeons show high concordance with board-certified dermatopathologists in the accurate and precise interpretation of histology slides in the setting of Mohs micrographic surgery.

An update on Epstein-Barr virus-and human T-lymphotropic virus type-1-induced cutaneous manifestations. CME Part II.

The Epstein-Barr virus (EBV) is a DNA virus that infects 90% of the human population, is responsible for certain cutaneous lymphomas (extranodal NK/T-cell lymhoma, hydroa vacciniforme lymphoproliferative disorder, lymphomatoid granulomatosis, others), and can be associated with a variety of cutaneous manifestations (eg, infectious mononucleosis, severe mosquito bite allergy, chronic active EBV disease, Gianotti-Crosti syndrome). EBV-related skin disorders are frequent in certain populations (South and Cental America, Africa, Asia, and Oceania) and can be diagnostically challenging. The human T-lymphotropic virus type-1 is a retrovirus, which is known to be associated with adult T-cell leukemia/lymphoma, neurologic disorders, but also cutaneous non-neoplastic manifestations (infective dermatitis, infections, and infestations). We performed an updated revision of the clinical dermatologic and histopathologic findings associated with the cutaneous non-neoplastic and preneoplastic disorders occurring in association with the EBV and human T-lymphotropic virus type-1.

An update on viral-induced cutaneous lymphoproliferative disorders. CME Part I.

Viral-induced cutaneous T-cell lymphomas are an uncommon group of lymphoproliferative disorders characterized by a viral infection of T and natural killer (NK) cells. This group of cutaneous T-cell lymphomas is more commonly encountered in Asians and Native Americans from Central and South America compared with Western populations. Viral-associated lymphoproliferative disorders include a spectrum of entities that range from nonneoplastic lesions, such as chronic active Epstein-Barr virus infection and infective dermatitis to malignant diseases, such as extranodal NK/T-cell lymphoma, hydroa vacciniforme-like T-cell lymphoma, and adult T-cell leukemia/lymphoma. This review article will focus on hydroa vacciniforme-like lymphoproliferative disorder, extranodal NK/T-cell lymphoma, adult T-cell leukemia/lymphoma, lymphomatoid granulomatosis, and Epstein-Barr virus-positive mucocutaneous ulcers. We will review the pathogenesis of these conditions and the challenges of making a timely diagnosis in early-stage disease and discuss the common clinicopathologic manifestations, mutational landscape, and approaches to treat these highly aggressive and frequently lethal types of lymphoma.

Dermatopathologic features of cutaneous squamous cell carcinoma and actinic keratosis: Consensus criteria and proposed reporting guidelines.

BACKGROUND: There is considerable variation in the literature regarding the dermatopathologic diagnostic features of and reporting guidelines for actinic keratosis (AK) and cutaneous squamous cell carcinoma (cSCC). OBJECTIVE: To develop consensus recommendations regarding diagnostic criteria, nomenclature, and reporting of AK and cSCC. METHODS: Literature review and cross-sectional multiround Delphi process including an international group of expert dermatopathologists followed by a consensus meeting. RESULTS: Consensus was achieved regarding the key dermatopathologic features necessary for diagnosing cSCC, AK, and associated variants; grading of degree of cellular differentiation in cSCC; utility of immunohistochemistry for diagnosis of cSCC; and pathologic features that should be reported for cSCC and AK. LIMITATIONS: Consensus was not achieved on all questions considered. CONCLUSION: Despite the lack of clarity in the literature, there is consensus among expert dermatopathologists regarding diagnostic criteria and appropriate reporting of AK and cSCC. Widespread implementation of these consensus recommendations may improve communication between dermatopathologists and clinicians, facilitating appropriate treatment of AK and cSCC.

Langerhans Cell Histiocytosis Evolving into Juvenile Xanthogranuloma: Two Linked Entities.

BACKGROUND: Langerhans cell histiocytosis (LCH) represents a myeloid clonal proliferation that involves the skin and other organs. Occasionally, cases of LCH evolve into juvenile xanthogranuloma (JXG). CASE PRESENTATION: A 7-month-old boy presented with an itchy, flaky rash resembling seborrheic dermatitis affecting the scalp and eyebrows. The lesions started at 2 months old. On physical examination, there were reddish/brown lesions on the trunk, denuded areas on the groin and neck, and a large lesion behind his bottom teeth. In addition, there were thick white plaques in his mouth and thick whitish material in both ears. A skin biopsy showed features of LCH. Radiologic examination demonstrated several osteolytic lesions. Chemotherapy produced marked improvement. A few months later, the patient developed lesions with clinical and histologic features of XG. CONCLUSION: A possible association between LCH and XG is explained by lineage maturation development. Chemotherapy may play a role in modifying the production of cytokines that enhance the transformation or 'maturation' of Langerhans cells into multinucleated macrophages (Touton cells) characteristic of a more favorable proliferative inflammatory condition.

Mucinous Syringometaplasia: Case Report and Review of the Literature.

ABSTRACT: Mucinous syringometaplasia is a rare and poorly recognized entity that usually presents as a warty tumor in acral regions. It is more frequent in men, and the age of presentation is variable. Typically, it has been reported as a solitary lesion with a warty appearance that occasionally can drain serous material. The affected sites include head, neck, breast, acral regions, and buttocks. The evolution over time is variable. The pathogenesis has not been elucidated. Diagnosis is established through histopathology, the characteristic feature is an epidermal invagination, which creates a structure similar to a "pore" at the dermal level. The clinical differential diagnosis is mainly with a viral wart, but it can also resemble basal cell carcinomas and other adnexal tumors. The treatment is surgical, and no recurrences have been reported to date. We describe the case of a 25-year-old woman who presented with a lesion on one of her eyelids. A shave removal of the lesion was performed, and the diagnosis was established by histopathologic examination.

Epithelioid Kaposi Sarcoma: A New Histological Variant.

ABSTRACT: Cutaneous Kaposi sarcoma (KS) covers a broad spectrum both clinically and pathologically. Some histological patterns of KS may be difficult to recognize and must be differentiated from other vascular neoplasms. We report on a 56-year-old Peruvian man who had been diagnosed with classical KS on the right foot 2 years before the present episode. He presented in our clinic with new lesions on the left foot. Histopathological findings included areas showing epithelioid cells with moderate pleomorphism, growing in solid sheets. Immunohistochemistry showed strong nuclear staining with a granular nuclear staining pattern for human herpesvirus 8 in the epithelioid cells. A diagnosis of epithelioid Kaposi sarcoma was made, which should be considered a new histological variant.

Microcystic Adnexal Adenoma: The Benign Counterpart of Microcystic Adnexal Carcinoma.

ABSTRACT: Microcystic adnexal carcinoma (MAC) is a low-grade malignant neoplasm of slow growth and low metastatic potential, but locally aggressive. Architecturally, MAC is usually a poorly circumscribed neoplasm that tends to extend deeply into the dermis and subcutaneous tissue. We present here a lesion in which the histopathologic study showed a well-demarcated nodular lesion involving the mid dermis and composed of small cystic keratinous structures, solid aggregates of pale squamous cells without cytologic atypia and ductal structures. Although these neoplastic components resembled those of MAC, the sharp delimitation of the lesion as well as the absence of deep extension and perineural involvement supported the benign nature of this lesion. We have named this neoplasm microcystic adnexal adenoma, as the benign counterpart of MAC.

Primary Cutaneous Aspergillosis in Immunocompetent Patients Due to Aspergillus niger: A Report of 4 Cases.

ABSTRACT: Primary cutaneous aspergillosis is a cutaneous fungal infection due to the direct inoculation of spores of Aspergillus species into the disrupted skin. Primary cutaneous aspergillosis presents with a variety of localized cutaneous lesions, such as erythematous macules, papules, plaques, or nodules that can progress to necrosis, erosion, ulceration, or fistulization. Many species of Aspergillus can cause the disease, and one of them is Aspergillus niger that rarely affects immunocompetent patients and that has peculiar characteristics on the histopathological examination. We present a series of 4 cases of immunologically competent patients presenting with primary cutaneous aspergillosis caused by A. niger.

Neuromuscular ultrasound for taxane peripheral neuropathy in breast cancer.

BACKGROUND: Our study aim was to evaluate neuromuscular ultrasound (NMUS) for the assessment of taxane chemotherapy-induced peripheral neuropathy (CIPN), the dose-limiting toxicity of this agent. METHODS: This cross-sectional study of breast cancer patients with taxane CIPN measured nerve cross-sectional area (CSA) by NMUS and compared with healthy historical controls. Correlations were determined between CSA and symptom scale, nerve conduction studies, and intraepidermal nerve fiber density (IENFD). RESULTS: A total of 20 participants reported moderate CIPN symptoms at a median of 3.8 months following the last taxane dose. Sural nerve CSA was 1.2 mm2 smaller than healthy controls (P ≤ .01). Older age and time since taxane were associated with smaller sural nerve CSA. For each 1 mm2 decrease in sural nerve CSA, distal IENFD decreased by 2.1 nerve/mm (R2 0.30; P = .04). CONCLUSIONS: These data support a sensory predominant taxane neuropathy or neuronopathy and warrant future research on longitudinal NMUS assessment of CIPN.

Morphea With Keloidal Features: A Case Report and Review of the Literature.

Keloidal morphea is a rare variant of scleroderma, which often can be clinically confused with keloid or scar formation. We report a 34-year-old woman with a medical history of asthma and Raynaud's phenomenon, presented for the evaluation and management of multiple erythematous hyperpigmented annular plaques reportedly developed after taking trimethoprim/sulfamethoxazole. An initial skin biopsy showed findings supportive of a drug eruption. She was treated with oral prednisone and achieved some improvement. She presented 1 year later with enlargement of the plaques and emergence of new lesions. Skin biopsies revealed an unremarkable epidermis with marked fibrosis of the mid-to-deep dermis with sparing of the papillary dermis, and superficial and deep perivascular and perieccrine lymphoplasmacytic inflammation. Verhoeff-Van Gieson staining demonstrated the loss of elastin fibers within the fibrotic areas of the biopsy specimens, which supported the diagnosis of keloidal morphea. Her laboratory tests were positive for antinuclear antibody (greater than 1:1280). She continued treatment with oral prednisone and topical steroids, and she showed improvement. This case highlights the importance of differentiating keloidal scleroderma from a hypertrophic scar or keloid to reveal an underlying systemic process. A correlation of clinical and histopathological findings is paramount to reach a correct diagnosis, ensure appropriate treatment, and monitor for comorbid disease.

Concurrent Metastatic Merkel Cell Carcinoma and Cutaneous Squamous Cell Carcinoma in the Same Lymph Node.

The coexistence of Merkel cell carcinoma (MCC) and squamous cell carcinoma (SCC) in the same cutaneous lesion is well known. The pathogenesis is believed to be distinct from conventional polyomavirus-related MCC, and it has a more aggressive course. Metastasis of MCC and SCC to the same lymph node is exceedingly rare with only one previously reported case in the English literature. To the best of our knowledge, this is the second case of MCC and SCC with metastasis to the same lymph node. Our case demonstrates the aggressive nature of the combined MCC and SCC in the setting of immunosuppression.