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.

Cutaneous Atypical Fibroxanthoma With Osteoclast-Like Giant Cell: A Rare but Diagnostic Pitfall.

BACKGROUND: Atypical fibroxanthoma (AFX) is a dermal-based, low-grade neoplasm with no specific lineage of differentiation. The occurrence of AFX with osteoclast-like giant cells is exceptionally rare. Less than 20 cases have been reported in the literature. CASE PRESENTATION: A 77-year-old man with a medical history of multiple basal and squamous cell carcinomas of the skin, presented with a progressively growing erythematous nodule on the sun-damaged right central parietal scalp. A shave biopsy showed a dermal spindle cell proliferation accompanied by numerous osteoclast-like multinucleated giant cells and predominant atypical mitotic figures. The immunohistochemical staining showed a diffuse positive staining for CD68 and SMA, patchy staining for CD10, and negative staining for SOX-10, pan-cytokeratin, CK5/6, S100, CD34, and desmin. The tumor was completely excised with negative margins. A subsequent follow-up over a period of 13 months showed no recurrence. CONCLUSION: Distinguishing AFX with osteoclast-like giant cells from both malignant and benign skin lesions with osteoclast-like giant cells is crucial. Although AFX tumors display worrisome malignant histologic features, most cases have a favorable prognosis with a local recurrence rate below 5% and exceedingly rare metastasis.

Bortezomib-Induced Reticular Eruption in Patient with Multiple Myeloma.

Bortezomib is the first proteasome inhibitor to treat a variety of malignancies and is currently part of the standard of care regimen for the initial treatment of patients with newly diagnosed multiple myeloma. While bortezomib is generally well tolerated, it has been associated with various side effects, which have limited its use in some patients. Here, we describe a unique case with histological confirmation of a reticular eruption that appeared at the site of a subcutaneous administration of bortezomib in a 62-year-old male who was newly diagnosed with IgG kappa multiple myeloma. A skin biopsy was performed, which revealed superficial perivascular dermatitis predominantly composed of lymphocytes with rare eosinophils. The patient was successfully treated with betamethasone dipropionate 0.05% cream. When consulted, dermatologists should advise the oncology team of multiple myeloma patients treated with bortezomib to maintain a high threshold before discontinuing the drug when a patient experiences an atypical, reticular rash following subcutaneous administration. Additionally, potent topical corticosteroids, such as betamethasone dipropionate 0.05% cream, should be considered in managing the cutaneous reticular eruptions related to bortezomib administration, in order to maintain an optimal treatment regimen for patients with multiple myeloma.

Halogen halos: Report of an early histopathologic finding in iododerma.

Iododerma is a rare cutaneous eruption that manifests after exposure to iodine-containing compounds, with few cases reported in the literature. Previous reports of this halogenoderma have described acellular halos simulating cryptococcus on histopathological examination but there is a paucity of reports of biopsies taken early in the disease course. We present a case of a 78-year-old patient who developed a papular eruption after receiving iodinated contrast. A skin biopsy taken within 24 h of the eruption showed a neutrophilic infiltrate with cryptococcal-like acellular haloed structures, indicating that the diagnostic finding may be found early in the disease course.