Hyperplasia of Arachnoid Trabecular Cells: A Hitherto Undescribed Lesion Observed in the Setting of Neurofibromatosis Type 1.

Central nervous system manifestations, a variety of benign and malignant tumors as well as non-neoplastic abnormalities, are found in over 70% of neurofibromatosis type 1 (NF1) patients. Herein, we report hitherto undescribed space-occupying lesions in the setting of NF1. We aimed to clarify their characteristics, especially whether they represent neoplastic or non-neoplastic (hyperplastic) lesions. All 3 cases were preoperatively assessed as non-neoplastic; 2 and 1 cases were suspected to be arachnoid cysts and dilation of subarachnoid space, respectively. However, all lesions were revealed to be whitish jelly-like masses by operation, and the histology composed of spindle cells resembling arachnoid trabecular cells with moderate cellularity and cellular uniformity gave an impression that these lesions may be neoplastic. In contrast, electron microscopic analysis showed that the characteristics of these cells were compatible with those of normal arachnoid trabecular cells. Furthermore, whole-exome sequencing and array comparative genomic hybridization did not show any obvious alterations suggestive of their neoplastic nature. DNA methylation analysis demonstrated that these lesions were epigenetically distinct not only from meningiomas but also from normal healthy meninges. In conclusion, considering the clinicopathologic aspects of the present lesions and the results of the molecular analysis that failed to suggest their neoplastic nature, they may represent previously unrecognized rare hyperplasia of arachnoid trabecular cells, which may be associated with NF1.

Autoimmune alopecia areata due to thymoma without myasthenia gravis: a case report.

BACKGROUND: Thymoma is associated with autoimmune diseases. Myasthenia gravis is frequently associated with thymoma, but cases of thymoma complicated by alopecia areata are very rare. In this report, we present a case of thymoma associated with alopecia areata, but without Myasthenia gravis. CASE PRESENTATION: A 60-year-old woman had a complaint of rapid progression of alopecia areata. A hair follicular biopsy was performed, which showed the infiltration of CD8-positive lymphocytes. She was prescribed topical steroids for 2 months prior to surgery, but her hair loss was not improved. Screening computed tomography showed a mass in the anterior mediastinum, which was suspected to be a thymoma. Myasthenia gravis was ruled out because she had no relevant symptoms or physical findings, and no anti-acetylcholine receptor antibodies were detected in serum. We performed a transsternal extended thymectomy based on a diagnosis of thymoma Masaoka stage I, without myasthenia gravis. Pathological examination showed Type AB thymoma, Masaoka stage II. The chest drainage tube was removed on postoperative day 1, and the patient was discharged on postoperative day 6. The patient has continued topical steroids and showed improvement 2 months postoperatively. CONCLUSIONS: Although alopecia areata is a rare complication in thymoma cases without myasthenia gravis, thoracic surgeons need to keep this condition in mind because alopecia reduces the patient's quality of life.

An autopsy case of granulomatous amebic encephalitis caused by Balamuthia mandrillaris involving prior amebic dermatitis.

An 82-year-old man, who was healthy and had worked as a farmer, experienced worsening neurological symptoms over a seven-month period, which eventually caused his death. Multiple fluctuating brain lesions were detected radiographically. Clinically, sarcoidosis was ranked high among the differential diagnoses because of the presence of skin lesions showing granulomatous inflammation, confirmed by biopsy. The patient's cerebrospinal fluid was also examined, but no definitive diagnosis was made while he was alive. An autopsy revealed multiple granulomatous amebic encephalitis lesions in the brain. Genetic and immunohistochemical analyses identified Balamuthia (B.) mandrillaris, a free-living ameba, which resides in soil and fresh water, as the causative organism. A retrospective examination revealed B. mandrillaris in the biopsied skin as well as cerebrospinal fluid, strongly suggesting that the ameba had spread into the brain percutaneously. Few studies have detailed the cutaneous pathology of B. mandrillaris infections. In general, granulomatous amebic encephalitis is extremely difficult to diagnose without autopsy, but the present case provides a clue that could allow similar cases to be diagnosed earlier; that is, the presence of skin lesions.