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Pseudobulbar affect
Pseudobulbar affect (PBA), also called pathological laughing and crying or emotional incontinence, is a neurological syndrome of sudden involuntary crying or laughing incongruent with mood, occurring in ALS, MS, stroke, TBI, and dementias; treated with dextromethorphan/quinidine.
Pseudobulbar palsy
Pseudobulbar palsy, also called supranuclear bulbar paralysis, is a syndrome from bilateral corticobulbar tract lesions causing spastic dysarthria, dysphagia, brisk jaw jerk, and pseudobulbar affect, seen in stroke, ALS, MS, and Parkinson's disease.
Pseudocyst of pancreas
Pancreatic pseudocyst, a complication of acute or chronic pancreatitis and trauma, is an encapsulated enzyme-rich fluid collection with a fibrous wall lacking epithelium, maturing after 4 weeks; symptomatic cysts are drained, usually endoscopically.
Pseudocyst of spleen
Pseudocyst of spleen, also called secondary or false splenic cyst, is an epithelium-free fibrous-walled cyst, usually post-traumatic, accounting for 70-80% of nonparasitic splenic cysts and managed by spleen-preserving drainage or surgery.
Pseudodiastrophic dysplasia
Pseudodiastrophic dysplasia is an extremely rare autosomal recessive skeletal dysplasia marked by short limbs, severe clubfoot, joint dislocations, platyspondyly, and scoliosis, first described in 1974.
Pseudoexfoliative open-angle glaucoma
Pseudoexfoliative open-angle glaucoma (PXG, PEXG, exfoliative glaucoma): secondary open-angle glaucoma from pseudoexfoliation material obstructing the trabecular meshwork; more aggressive than POAG, needing earlier surgery.
Pseudofolliculitis barbae
Pseudofolliculitis barbae (PFB), razor bumps, is a chronic inflammatory ingrown-hair disorder of shaved beard and neck skin, predominantly affecting Black men with tightly curled hair; treated with grooming changes, topicals, and laser hair removal.
Pseudohypoaldosteronism type 1
Pseudohypoaldosteronism type 1 (PHA1), a rare hereditary aldosterone-resistance disorder causing neonatal salt wasting, hyponatremia, and hyperkalemia; renal form from NR3C2 mutations, generalized form from ENaC subunit genes.
Pseudohypoaldosteronism type 2
Pseudohypoaldosteronism type 2, or Gordon syndrome (PHAII, familial hyperkalemic hypertension), is a rare genetic distal-tubulopathy causing hypertension, hyperkalemia, and metabolic acidosis with normal GFR, from WNK1, WNK4, KLHL3, or CUL3 mutations, treated with thiazides.
Pseudohypoparathyroidism type 1A
Pseudohypoparathyroidism type 1A (PHP1A, OMIM 103580), Albright hereditary osteodystrophy with hormone resistance: a rare disorder from maternally inherited GNAS mutations causing PTH and TSH resistance, hypocalcemia, hyperphosphatemia, brachydactyly, and obesity.
Pseudohypoparathyroidism type 1B
Pseudohypoparathyroidism type 1B (PHP1B, OMIM 603233), a rare GNAS imprinting disorder with isolated renal PTH resistance causing hypocalcemia, hyperphosphatemia, elevated PTH, mild TSH resistance, no AHO features, treated with calcitriol and calcium.
Pseudohypoparathyroidism type 1C
Pseudohypoparathyroidism type 1C (PHP1C, PHP-Ic, OMIM 612462), a rare autosomal dominant GNAS disorder with PTH resistance, hypocalcemia, hyperphosphatemia, and Albright hereditary osteodystrophy but normal Gsα activity in vitro; now grouped as iPPSD2.
Pseudohypoparathyroidism type 2
Pseudohypoparathyroidism type 2 (PHP2, PHP II, ORPHA:94090) is a rare PTH-resistance disorder with hypocalcemia, hyperphosphatemia, elevated PTH, no Albright hereditary osteodystrophy, normal urinary cAMP response, and deficient phosphaturia.
Pseudomyogenic hemangioendothelioma
Pseudomyogenic hemangioendothelioma (epithelioid sarcoma-like hemangioendothelioma) is a rare intermediate vascular tumor of skin, soft tissue, and bone in young men, multifocal, locally recurrent, rarely metastatic, defined by FOSB gene fusions.
Pseudomyotonia
Pseudomyotonia (ICD-11 8C71.5), also called false myotonia, is delayed muscle relaxation mimicking myotonia without myotonic discharges on EMG; causes include Isaacs syndrome, Hoffmann's hypothyroid myopathy, Brody disease, and central lesions.
Pseudomyxoma peritonei
Pseudomyxoma peritonei (PMP), or jelly belly, a rare mucin-filling peritoneal cancer usually from a ruptured appendiceal mucinous neoplasm; treated with cytoreductive surgery plus HIPEC, 1-2 per million incidence.
Pseudoporphyria
Pseudoporphyria, also called pseudoporphyria cutanea tarda, is a drug- or UV-triggered blistering photosensitive skin disorder mimicking porphyria cutanea tarda but with normal porphyrin tests; naproxen and dialysis are leading causes.
Pseudopseudohypoparathyroidism
Pseudopseudohypoparathyroidism (PPHP, pseudo-PHP), also iPPSD2, a rare genetic disorder with Albright hereditary osteodystrophy features but no PTH resistance, caused by paternally inherited GNAS mutations; maternal inheritance of the same mutation causes PHP-Ia.
Pseudostratified columnar epithelium
Pseudostratified columnar epithelium, also called respiratory epithelium when ciliated, is a single-layer tissue whose staggered nuclei mimic stratification; it lines the airways and male reproductive tract and drives mucociliary clearance.
Pseudounicornuate uterus
Pseudounicornuate uterus (Utérus pseudo-unicorne, ORPHA:180079, ICD-10 Q51.4): rare non-syndromic Müllerian malformation with a single-horned crescent uterus plus a rudimentary second horn, often with urinary tract anomalies.
Pseudoxanthoma elasticum
Pseudoxanthoma elasticum (PXE, Grönblad-Strandberg syndrome): rare autosomal recessive ABCC6 disorder causing calcification of elastic fibers in skin, retina, and arteries; low pyrophosphate; no causal treatment yet.
Pseudoxanthoma elasticum-like papillary dermal elastolysis
PXE-PDE, PXE-like papillary dermal elastolysis, is a rare acquired elastolytic skin disorder with yellowish cobblestone papules on the neck of postmenopausal women, mimicking inherited pseudoxanthoma elasticum but lacking systemic involvement.
Psilocin
Psilocin (4-hydroxy-N,N-dimethyltryptamine) is the active metabolite of psilocybin, isolated from Psilocybe mexicana by Hofmann in 1958; a 5-HT2A agonist causing psychedelic effects.
Psilocybin
Psilocybin, also known as psilocin phosphate ester, is a naturally occurring psychedelic compound produced by certain mushrooms that the body converts to psilocin, an investigational treatment for depression.
Psilocybin-assisted psychotherapy
Psilocybin-assisted psychotherapy, also known as psilocybin therapy, is a treatment in which supervised psilocybin dosing sessions are embedded in structured psychological support, studied mainly for treatment-resistant depression.
PSMA PET
PSMA PET is a nuclear medicine imaging method that detects and stages prostate cancer using radiotracers binding prostate-specific membrane antigen, standard of care since 2020.
PSMPD trial
PSMPD trial (NCT05239065), Personalized Stress Management With Application of Portable Devices in Occupational Populations: nonrandomized controlled study in two Wuhan hospitals testing Huawei-device-supported stress coaching for 245 healthcare workers; PSS improved, HRV did not differ.
Psoas major muscle
Psoas major: deep core muscle joining the iliacus as the iliopsoas, the thigh's primary flexor; inserts separately on the lesser trochanter and crosses the ~3 o'clock psoas valley of the acetabular rim.
Psoriasiform napkin dermatitis
Psoriasiform napkin dermatitis (PND), ICD-11 EH40.02, is a sharply marginated scaly diaper-area eruption of infancy resembling psoriasis; HLA studies and follow-up data distinguish it from true psoriasis, though some cases eventuate into napkin psoriasis.
Psoriasis
Psoriasis is a chronic immune-mediated inflammatory disease of skin, nails, and joints affecting 2-3% of people, driven by the IL-23/Th17 axis, with plaque, guttate, pustular, inverse, and erythrodermic types, treated with topicals, phototherapy, systemics, and biologics.