Human Pathology Reports最新文献

Signet ring cell lymphoma is an exceedingly rare subtype of non-Hodgkin lymphoma that was originally thought to be a morphologic variant of follicular lymphoma. To date, 56 cases have been reported, with the majority occurring in lymph nodes and bone marrow. Herein, we report a case of a 37-year-old female who presented with a left inguinal mass and high suspicion of lymphoma that was rendered on MRI. A successful ultrasound-guided core biopsy was performed. Pathologic examination revealed a diffuse large B-cell lymphoma (DLBCL) with unique signet ring histology and post-germinal center phenotype. In-situ hybridization showed an isolated BCL-6 gene rearrangement and confirmed the absence of a double-hit phenotype. This case would be situated as the second case of activated B-cell (ABC) signet ring lymphoma and the first case to arise in this anatomic location. The patient recently initiated therapy with a standard six-cycle regimen of R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone).

We describe a case of EBV-positive lymphoma with characterization of histological, immunophenotypic, and molecular features and a brief literature review of similar entities. Atypical large lymphoid cells with pleomorphic nuclei, moderate eosinophilic cytoplasm, and high mitotic activity were noted along with positivity for CD20, OCT2, CD79a, CD19, CD2, perforin, CD30, MUM1, c-MYC, BCL-2, and CD45. Dim positivity with PAX5 and weak cytoplasmic staining with CD3 was noted. These cells were negative for CD4, CD5, CD7, CD8, CD10, BCL-6, CD15, EMA, HHV-8, TdT, Cyclin-D1 and Granzyme B. EBV encoded RNA in situ hybridization was diffusely positive in atypical cells. Both T and B cell gene rearrangements were detected which demonstrates lineage overlap in EBV-positive large cell lymphomas, supported by B and T-cell receptor gamma gene rearrangement proven on molecular studies. The presence of similar entities may lead to potential misclassification of neoplasms. No prognostic significance of this finding was identified.

Alveolar soft part sarcoma (ASPS) is a potentially lethal soft tissue tumor with a xropensity for distant metastasis. We report an exceedingly rare case of an ASPS arising from the pectoralis major in a young woman, with initial clinical findings mimicking a breast mass. We present the radiographic, immunohistochemical, and molecular workup leading to the correct diagnosis, with review of the differential diagnosis.

Background

Epidermal growth factor receptor (EGFR) is one of the driver mutations in advanced Non – Small Cell Lung Carcinoma (NSCLC) and is prominently chosen to advocate personalized treatment approaches. The advancing field of molecular pathology along with the introduction of the EGFR TKIs has profoundly changed the therapeutic landscape of the NSCLC. But therapeutic decision might be challenging when different testing methods yield non-identical results.

Method

A patient diagnosed with lung carcinoma negative for ALK and ROS1 rearrangements was subjected to EGFR testing by Therascreen, plasma based genotyping by Roche cobas V2 and bioRAD droplet digital PCR. Taking into consideration the variant results, both Therascreen and Roche cobas V2 testing was again performed on fresh biopsies.

Result

Single gene testing of EGFR by Therascreen was negative. Plasma based genotyping for EGFR mutations using the Roche cobas V2, yielding a del19 mutant whereas, bioRAD droplet digital PCR revealed del19 wild type along with small clone of T790M. The Therascreen assay was negative, whereas the Roche cobas V2 yielded a positive del19 mutant. The T790M clone was not detected by cobas neither in plasma nor in tissue.

Conclusion

In view of the absence of T790M mutant, the patient was planned first line therapy of Osimertinib. The choice of testing modality decides the suitable therapy for the patient to a great extent. Although tissue genotyping is still the gold standard, using liquid biopsy genotyping in addition to tissue genotyping improves the discovery of sensitizing mutations in targetable genes, ultimately leading to better patient outcomes.

We report a 38-year-old female with a history of primary pelvic PEComa and subsequent metastatic PEComa to the mediastinum who presented with recurrent mediastinal metastasis in April 2021. At initial presentation in 2010, the patient reported a three-month history of abdominal pain, hot flashes, night sweats, and a one-day history of bloating. Surgery revealed an 18-cm multilobulated pelvic mass involving the posterior uterus, bladder, and bilateral adnexa. Histology showed spindled and epithelioid tumor cells immunopositive for HMB-45, desmin, TFE3, SMA, caldesmon, Melan-A and calretinin. Cytokeratin, S-100, inhibin, myogenin, and OCT3/4 immunostains were negative. In 2013 the patient re-presented with chest pain. Imaging confirmed a mediastinal mass involving the pericardium with histology resembling the previous pelvic mass. Following initial resection and mTOR therapy, the mediastinal mass recurred once in 2015 with similar histologic findings. This case provides the first description of a malignant pelvic PEComa metastasizing to the mediastinum, and demonstrates the challenges associated with diagnosing metastatic PEComa. Though malignant PEComa with metastasis to the mediastinum is rare, it is important to recognize the natural process of this tumor to ensure adequate follow-up and patient care.

We report a kidney transplant recipient in their early twenties with infantile nephropathic cystinosis and EBV viremia who presented with right flank pain, night sweats, and right lower quadrant abdominal tenderness. A CT scan of the abdomen demonstrated mesenteric adenopathy. A laparoscopic mesenteric lymph node biopsy was performed with a concern for post-transplant lymphoproliferative disorder (PTLD). Positive birefringent crystals were identified within the tissue macrophages of benign reactive lymph nodes. Immunohistochemical staining and flow cytometry confirmed polyclonal B-cells without evidence of a clonal B-cell population supportive of PTLD. We report intracellular birefringent crystals within lymph nodes in a patient with infantile cystinosis. We review the clinical history of the patient and the pathologic analysis to evaluate for possible PTLD.

Follicular dendritic cell sarcomas (FDCS) are rare tumors derived from non-migrating antigen-presenting cells. They are distinguished from other histiocytic and dendritic cells by their immunophenotype, which supports a mesenchymal, non-myeloid stem cell origin. A 63-year-old woman reported painless epigastric fullness for 20 years, and was eventually found to have a 16.0 cm mass indistinguishable from the pancreas and surrounding tissue. Initial needle biopsy showed a high-grade epithelioid malignant neoplasm. A Whipple resection was ultimately performed, and evaluation revealed a malignant epithelioid neoplasm with histologic and immunophenotypic features of FDCS. FDCS is a rare tumor that can involve virtually any nodal or extranodal site, and to our knowledge this is the first reported case of FDCS of the pancreas. This case report emphasizes that FDCS should be considered in the differential diagnosis of pancreatic neoplasms with focal cytokeratin positivity, so that appropriate IHC testing with FDC-associated markers can be used to confirm the diagnosis.

Extra-ovarian sex cord-stromal tumors are often clinically and radiologically considered as ovarian malignancies. Pathologically, this poses a diagnostic challenge. Here, we present a case of extra-ovarian cellular fibroma in an eighty-four-year-old woman. The pedunculated solid mass was located in the posterior cul-de-sac, and intraoperative frozen section diagnosis was leiomyoma or fibroma. Both ovaries and salpinges were normal. A laparoscopy-assisted mass excision and bilateral salpingo-oophorectomy were performed. Microscopically, cellularity showed increased alternative pattern, mild cytological atypia, and the mitotic count was 2/10 high-power fields. Tumor cells were immunoreactive to antibodies produced against Wilms tumor-1 and progesterone receptors. The cells were weakly positive for inhibin-alpha and smooth muscle actin. The pathological diagnosis was an extra-ovarian cellular fibroma. We summarized the cases of extra-ovarian pure stromal tumors reported to date and compared them with our case. Immunohistochemical studies are essential because the pathological differential diagnosis of extra-ovarian fibromas includes extra-gastrointestinal stromal tumors and leiomyomas. Cellular fibromas should be carefully diagnosed due to their tendency to recur.

Ras-associated autoimmune leukoproliferative disorder (RALD) is a nonmalignant lymphoproliferative disease associated with somatic RAS mutations. It is characterized by autoimmune disease, lymphadenopathy, splenomegaly and monocytosis. Less than 30 cases of RALD have been reported in the literature. We report a 20-year-old female patient who presented with lymphadenopathy, splenomegaly and autoimmune cytopenia, without increased double-negative T-cells. We describe the histopathological features seen in this patient’s lymph node and bone marrow. The lymph node showed paracortical expansion by histiocytes and T-cells, with reactive follicular hyperplasia and progressive transformation of germinal centers. The bone marrow demonstrated hypercellular marrow with increased histocytes, T-cells, plasma cells, and mild diffuse fibrosis. The 220-gene Next Generation Sequencing (NGS) identified a somatic KRAS gene mutation (KRAS p.A146P) with a 34% of variant allele frequency (VAF), which is not codon 12 or 13 of the KRAS gene frequently described in RALD patients. A diagnosis of RALD was proposed. The diagnosis of RALD requires the integration of multifaceted methods including clinical information, laboratory tests, histology, and molecular tests. The histological and molecular conformation we provide in this case report is a valuable addition to understanding the spectrum of RALD presentation.