Journal of Cutaneous Pathology最新文献

An 11-year-old female was referred from an outside institution after a diagnostic biopsy and subsequent excision of a progressively enlarging reddish-brown nodule demonstrated features concerning for a balloon cell nevus with severe atypia versus a high-grade melanocytoma. Upon review of the initial biopsy specimen and molecular data, we favored the diagnosis to be consistent with a high-grade melanocytoma with balloon cell changes while considering the possibility of balloon cell melanoma due to concerning histopathologic and genetic abnormalities. In this case study, we discuss critical diagnostic considerations in this rare pediatric case and highlight important pathologic and clinical features of melanocytomas and balloon cell melanoma.

Paget disease is an intraepithelial neoplastic proliferation, commonly occurring in the breast and apocrine-rich areas, often associated with an underlying internal malignancy. Extramammary Paget disease (EMPD) of the oral cavity is exceedingly rare, with only eight reported cases, four of which were associated with an underlying internal malignancy. Here, we report a case of oral EMPD involving the buccal mucosa and gingiva of an 81-year-old male with no known underlying internal malignancy. The Paget cells were positive for CK7, CK20, CAM5.2, and androgen receptor, but negative for SOX10 and p63. The immunophenotype, association with internal malignancies, and treatment approaches for oral EMPD are reviewed.

Cutaneous spindle cell neoplasms can be challenging to diagnose using routine histopathological techniques alone, and the growing repertoire of molecular studies can assist in diagnosis. We describe a cutaneous spindle cell neoplasm characterized by a COL3A1::PDGFRA rearrangement predicted to lead to constitutive activation of the PDGFRA kinase domain. The lesion shows some similarities to dermatofibrosarcoma protuberans and also benign and epithelioid fibrous histiocytomas but is distinct from these entities histopathologically and molecularly. This tumor is considered to represent an entity in the spectrum of PDGFR-driven cutaneous mesenchymal neoplasms.

Melanoma, with its diverse histopathologic characteristics, can mimic both benign nevi and neoplasms of various cell lineages. Immunohistochemistry (IHC) can play a vital role in melanoma diagnosis, particularly when the cell lineage is unclear on hematoxylin and eosin sections. Commonly utilized IHC stains for melanoma diagnosis include SOX10, Melan-A, and S100. A relatively novel stain, PReferentially expressed Antigen in MElanoma (PRAME), is also proving useful in accurate melanoma diagnosis. However, none of these stains are completely specific to melanocytes or melanoma, and misinterpretation can lead to incorrect diagnoses. This report presents a unique case of triple-negative breast carcinoma (TNBC) metastatic to the skin exhibiting histopathologic characteristics similar to melanoma, including positivity for SOX10 and PRAME. Our aim is to highlight TNBC metastatic to the skin as a potential diagnostic pitfall.

Cytophagic histiocytic panniculitis (CHP) is associated with a number of systemic conditions and is characterized by the presence of benign phagocytic histiocytes (“bean bag cells”), including phagocytosed erythrocytes, leukocytes, and platelets. We describe a case of a 72-year-old female who presented with a papular eruption that clinically mimicked pityriasis lichenoides et varioliformis acuta (PLEVA). Given that her skin biopsy had multiple features concerning PLEVA, this diagnosis was classified as a superficial pityriasis lichenoides-like variant of CHP. The histopathologic presence of cytophagic histiocytosis prompted workup for a systemic malignancy, leading to a diagnosis of underlying acute monocytic leukemia of myeloid lineage.

Mycosis fungoides (MF) has been widely reported to mimick a considerable number of different dermatoses, including scarring alopecia, bullous dermatoses or cysts, and comedones. In atypical presentations, histopathology is essential for the diagnosis. We present two cases of MF with clinical urticarial lesions and a striking blood involvement that responded to mogamulizumab treatment. Histopathologically, both cases had classic MF features and shared a peculiar immunophenotype, with positivity for CD25 and FOXP3. Differential diagnoses included urticarial lymphomatoid drug reactions and other lymphomas, like T-cell prolymphocytic leukemia, atypical Sézary syndrome, or adult T-cell lymphocytic leukemia. A low suspicion threshold is necessary for the diagnosis of atypical presentations of MF.

During routine dermatologic examination, a 77-year-old male was noted to have a firm blue subcutaneous nodule on his right lateral upper back. His past medical history included metastatic melanoma of unknown primary involving right and left axillary lymph nodes, treated with ipilimumab/nivolumab with complete response, and subsequent primary uveal melanoma. The subcutaneous nodule was located near his previous right axillary scar for metastatic melanoma. Excision of the nodule showed a plexiform neoplasm involving mid and deep dermis composed of spindle and epithelioid atypical cells admixed with numerous melanophages. Central necrosis was present. Immunohistochemical studies revealed the tumor cells to be diffusely positive for HMB45, with retained expression of BAP1 and p16. The tumor cells were negative for PRAME, nuclear expression of β-catenin, LEF1, and BRAF V600E. Molecular studies demonstrated BAP1 and GNA11 somatic mutations, a profile different from that exhibited by his prior melanoma. Collectively, these data were interpreted as a metastasis from uveal melanoma and not a recurrence of his metastatic likely cutaneous melanoma after complete response to immunotherapy. This case emphasizes the importance of molecular studies for definitive diagnosis in challenging clinical situations, especially when there is discordance among histopathological, immunohistochemical, and molecular studies. Integration of clinical, histopathological, and molecular features is warranted.