Small variations in ice composition and layer thickness explain bright reflections below martian polar cap without liquid water.

Abnormally bright radar reflections below the Martian south polar layered deposit were originally interpreted as evidence of subglacial liquid water. However, unlike on Earth, conditions beneath the Martian ice are too cold to create or maintain meltwater. In this work, we use radar reflectivity simulations to show that the strong reflections can instead be caused by constructive interference between dusty ice layers that are more closely spaced than the radar resolution. Unlike previous hypotheses, interference does not require anomalous subsurface conditions or exotic materials to be present beneath the ice. In addition, interference between thin layers can explain the variable power of radar returns beneath the entire ice sheet and does not require different mechanisms to be responsible for reflections in different regions.

Ganglioglioma with anaplastic/high-grade transformation: Histopathologic, molecular, and epigenetic characterization of 3 cases.

Ganglioglioma (GG) with anaplasia (anaplastic ganglioglioma) is a rare and controversial diagnosis. When present, anaplasia involves the glial component of the tumor, either at presentation or at recurrence. To date, most published cases lack molecular characterization. We describe the histologic and molecular features of 3 patients presenting with BRAF p. V600E-mutant GG (CNS WHO grade 1) with high-grade glial transformation at recurrence. The tumors occurred in pediatric patients (age 9-16 years) with time to recurrence from 20 months to 7 years. At presentation, each tumor was low-grade, with a BRAFV600E-positive ganglion cell component and a glial component resembling pleomorphic xanthoastrocytoma (PXA) or fibrillary astrocytoma. At recurrence, tumors resembled anaplastic PXA or high-grade astrocytomas without neuronal differentiation. CDKN2A homozygous deletion (HD) was absent in all primary tumors. At recurrence, 2 cases acquired CDKN2A HD; the third case showed loss of p16 and MTAP immunoexpression, but no CDKN2A/B HD or mutation was identified. By DNA methylation profiling, all primary and recurrent tumors either grouped or definitely matched to different methylation classes. Our findings indicate that malignant progression of the glial component can occur in GG and suggest that CDKN2A/B inactivation plays a significant role in this process.

Cutaneous metastasis of ovarian carcinoma with shadow cells mimicking a primary pilomatrical neoplasm.

Shadow cells are characteristic of pilomatricoma, although they have been described in other cutaneous and visceral neoplasms, particularly endometrioid adenocarcinomas of the female genital tract. We describe a metastasis of an ovarian endometrioid adenocarcinoma with shadow cells to the skin that was initially misinterpreted as a pilomatricoma. We compare the histology of the ovarian neoplasm to 21 pilomatricomas. This is the first reported case of a cutaneous metastasis of a visceral neoplasm mimicking a primary pilomatrical neoplasm.

Disseminated Sporotrichosis With Brain Abscesses in an HIV-Infected Patient.

Sporotrichosis is a mycotic infection caused by the Sporothrix schenckii species complex. It typically presents as a localized, mostly cutaneous or lymphocutaneous infection, but has been increasingly presenting as a disseminated infection in immunocompromised individuals, especially in HIV/AIDS patients. We also included a literature review of sporotrichosis in this patient population. The aim of this case report is to raise awareness about atypical presentations of sporotrichosis in an attempt to decrease the time to diagnosis, initiate treatment earlier when infection is suspected, and improve overall survival in vulnerable patient populations.

Case Report: Management of rectal squamous cell carcinoma - a treatment dilemma.

Primary rectal squamous cell carcinoma is rare compared to adenocarcinoma, which is the predominant histologic type most commonly discovered at the time of colorectal carcinoma diagnosis. Due to the infrequent nature of this malignancy, data on tumor pathogenesis and risk factors remains sparse. Moreover, no standardized therapeutic regimen exists. This report describes a case of advanced rectal squamous cell carcinoma diagnosed in a 46-year-old female who initially presented with abdominal pain. Her clinical course was uncomplicated and she responded well to the selected therapy. Much work remains to be accomplished for patients with rectal squamous cell carcinoma.

Primary Cutaneous Diffuse Large B-Cell Lymphoma, Leg Type: A Case Report.

Primary cutaneous diffuse large B-cell lymphoma, leg type, is an exceedingly rare and aggressive variant of primary cutaneous lymphoma. An 84-year-old male presented to an oncologist for new skin lesions on his abdomen and right thigh. Excisional biopsy followed by histopathology and immunohistochemistry confirmed the diagnosis of primary cutaneous diffuse large B-cell lymphoma, leg type. His clinical course was complicated by multiple relapses and refractory disease. Ultimately, he achieved complete response with fourth-line ibrutinib therapy. Due to the contentious nature of this disease, poor prognosis, and higher rates of recurrence, prompt identification and aggressive treatment are recommended. Given the different cellular pathways and genomic alterations identified in its carcinogenesis, various chemotherapy regimens and targeted immunotherapies have emerged as potential therapeutic options to halt disease progression and prevent future relapses.

SMARCB1/INI1-Deficient Extrarenal Rhabdoid Tumor: A Case Report of a Rare and Aggressive Soft Tissue Sarcoma.

Malignant SMARCB1/INI1-deficient extrarenal rhabdoid tumors are aggressive tumors that are extremely rare in adults. A 56-year-old male presented with the chief complaints of unilateral lower abdominal and pelvic pain. He underwent urgent surgical intervention and mass resection with tissue sampling. After pathology confirmed the diagnosis, systemic chemotherapy with vincristine, doxorubicin plus ifosfamide, and mesna was administered. Following treatment, he experienced a durable and long-lasting response to therapy for this aggressive and rare soft tissue sarcoma. To date, the patient remains in complete remission following the cessation of chemotherapy. Malignant SMARCB1/INI1-deficient extrarenal rhabdoid tumors are aggressive neoplasms that are extremely rare in adults. We report a rare case of such a tumor and review the literature for its molecular, clinical, and imaging features.

Leptomeningeal Carcinomatosis: A Case Report of Metastatic Triple-negative Breast Adenocarcinoma.

A 55-year-old female presented to the emergency department with seizures, left hemiparesis, and memory loss. Her past medical history was notable for a right triple-negative breast adenocarcinoma that was diagnosed approximately two years prior. She underwent treatment with chemotherapy, right breast lumpectomy, and radiation near her rural hometown. Radiologic studies were performed in the emergency department. Brain imaging revealed a new 2-cm mass in the left breast and a 4-cm left frontal lobe brain lesion. She underwent an urgent craniotomy. Immunohistochemical staining of the brain tumor tissue suggested metastatic triple-negative breast adenocarcinoma. She was discharged with recommendations to follow up with her prior oncologist near her home for systemic chemotherapy. Three months after metastatic breast cancer to the brain was diagnosed, the patient experienced headaches, fever, and nuchal rigidity. MRI of the brain showed new leptomeningeal enhancement. A lumbar puncture with a cerebrospinal fluid analysis revealed the presence of malignant cells. Together with imaging and cerebrospinal fluid findings, leptomeningeal carcinomatosis was diagnosed. This case report presents an uncommon but well-known complication of breast cancer.

Colonic Metastasis of Lung Adenocarcinoma: A Case Report.

Colonic metastases are extremely rare, regardless of primary lung cancer type. A 64-year-old female was referred to the hospital by her gastroenterologist after a same-day colonoscopy revealed a large rectosigmoid mass resulting in near total rectal occlusion. On admission, she complained of abdominal pain and constipation. She had a past medical history of non-small cell lung cancer (T1bN3M0 stage IIIB), diagnosed one year prior. She was thought to be in remission following radiation and immunotherapy with pembrolizumab. She underwent urgent surgical intervention and mass resection with tissue sampling. Pathology confirmed the diagnosis of metastatic lung adenocarcinoma. Systemic chemotherapy with pemetrexed and carboplatin followed by localized radiation to the pelvic region was administered. A refractory pelvic region tumor growth was evident on subsequent imaging. Cessation of chemoradiation therapy occurred after the patient experienced a debilitating stroke and she was transferred to hospice care. Colonic metastasis should be considered when patients with a history of primary lung cancer have abdominal symptoms.