RESUMEN
Pituitary carcinoma is a condition defined by metastasis of a pituitary tumor to a distant location, and it is a very rare type of adenohypophyseal tumor. We present a case of a 29-year-old female who was followed up in our Endocrinology Department. Past medical history included the diagnosis of Cushing disease and transsphenoidal tumor resection at 12 years of age, followed by transcranial resection two years later because of persistently elevated adrenocorticotropic hormone (ACTH). Despite the surgical management, the patient persisted with increased ACTH and hypercortisolism, and, thus, bilateral adrenalectomy was performed a year later. Two years after the procedure, the patient presented with a newly diagnosed pituitary macroadenoma, and the diagnosis of Nelson syndrome was made. Linear accelerator radiotherapy was given, which reduced the size of the tumor. Later, several imaging studies showed multiple lesions on the falx cerebri, posterior clinoid process, retroclival region, cerebellopontine angle, pterygopalatine fossa, infratentorial region, and posterior ethmoidal cells. Biopsy and immunohistochemistry of the falx cerebri lesions described ACTH-producing pituitary adenocarcinoma. Treatment was given with intramuscular octreotide, dabrafenib, and trametinib. Despite persistently elevated ACTH levels, the patient has since remained clinically stable, without new development or worsening of symptoms. There are three unique aspects of our case. First, we reported an unusual presentation of this disease, since the patient in our case was a female with an early age of onset. Second, this is the first reported case demonstrating pituitary carcinoma in the falx cerebri. Third, the prognosis of pituitary carcinoma is usually very poor, and mortality is extremely high; however, the patient in our case has been followed up for seven years since the diagnosis of the metastatic lesions and has remained clinically stable.
RESUMEN
The hippocampus is crucial for acquiring and retrieving episodic and contextual memories. In previous studies, the inactivation of dentate gyrus (DG) neurons by chemogenetic- and optogenetic-mediated hyperpolarization led to opposing conclusions about DG's role in memory retrieval. One study used Designer Receptors Exclusively Activated by Designer Drugs (DREADD)-mediated clozapine N-oxide (CNO)-induced hyperpolarization and reported that the previously formed memory was erased, thus concluding that denate gyrus is needed for memory maintenance. The other study used optogenetic with halorhodopsin induced hyperpolarization and reported and dentate gyrus is needed for memory retrieval. We hypothesized that this apparent discrepancy could be due to the length of hyperpolarization in previous studies; minutes by optogenetics and several hours by DREADD/CNO. Since hyperpolarization interferes with anterograde and retrograde neuronal signaling, it is possible that the memory engram in the dentate gyrus and the entorhinal to hippocampus trisynaptic circuit was erased by long-term, but not with short-term hyperpolarization. We developed and applied an advanced chemogenetic technology to selectively silence synaptic output by blocking neurotransmitter release without hyperpolarizing DG neurons to explore this apparent discrepancy. We performed in vivo electrophysiology during trace eyeblink in a rabbit model of associative learning. Our work shows that the DG output is required for memory retrieval. Based on previous and recent findings, we propose that the actively functional anterograde and retrograde neuronal signaling is necessary to preserve synaptic memory engrams along the entorhinal cortex to the hippocampal trisynaptic circuit.
RESUMEN
El tumor triquilemal proliferante es una dermatosis tumoral poco frecuente y derivada de la capa externa de la raíz del folículo piloso. Generalmente, es de características benignas, tiende a ser recidivante y se han reportado casos de transformaciones malignas en la bibliografía mundial. El caso trata de una paciente femenina de 59 años, con una neoformación exofítica nodular lobulada de crecimiento lento en piel cabelluda, de 5 años de evolución, con recidivas después de 3 cirugías. No se documentó compromiso óseo ni cerebral en los estudios de gabinete. La biopsia mostró proliferación de nidos de células escamosas en dermis, separados por bandas de tejido fibroso de la epidermis. El abordaje quirúrgico es el tratamiento de elección de esta patología.
Proliferating trichilemmal tumor is a rare cutaneous neoplasm originating from the outer root sheath of a hair follicle. It is usually benign, tends to recur and cases of malignant transformations have been reported in worldwide literature. Our case relates to a 59-year-old female with a slow-growth exophytic nodular lobulated tumor with a 5-year development and recurrences after 3 previous surgeries. Clinical imaging showed no skull or cerebral involvement. The biopsy showed proliferating squamous cell clusters in dermis separated by fibrous tissue in the epidermis. Surgical excision is the best choice of treatment for this disease.