Human health and medicine

Blarcamesine

Blarcamesine (ANAVEX2-73) is an investigational oral activator of the sigma-1 receptor developed by Anavex as a treatment for Alzheimer's disease, which the EMA recommended rejecting in December 2025.

Blaschko's lines

Blaschko's lines, or lines of Blaschko, are invisible human skin patterns tracing embryonic epidermal cell migration, described by Alfred Blaschko in 1901; visible only when cutaneous mosaicism or diseases like lichen striatus follow them.

Blast crisis in chronic myelogenous leukemia

Blast crisis, or blast phase, is the final phase of chronic myelogenous leukemia, defined by 20% or more immature leukemic blasts in blood or bone marrow.

Blast injury

Blast injury: trauma from explosion exposure, classified by DoD taxonomy into primary (overpressure), secondary (fragments), tertiary (displacement), quaternary, and quinary categories; blast lung is the most common fatal primary injury among survivors.

Blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm (BPDCN), formerly blastic NK-cell lymphoma, is a rare aggressive CD4+/CD56+/CD123+ hematologic malignancy of plasmacytoid dendritic cell precursors, presenting as purple skin lesions, treated with tagraxofusp and pivekimab sunirine.

Blastocystosis

Blastocystosis is intestinal colonization by Blastocystis (formerly B. hominis), a unicellular stramenopile parasite found worldwide in humans and animals; nine subtypes infect humans, most carriers have no symptoms, and its disease role and treatment remain debated.

Blastomycosis

Blastomycosis (North American blastomycosis, Gilchrist disease) is a fungal pneumonia from inhaling Blastomyces spores in soil, endemic to US Midwest and Canada, treated with itraconazole or amphotericin B.

Blau syndrome

Blau syndrome (early-onset sarcoidosis) is a rare autosomal dominant NOD2 gain-of-function granulomatous disease with childhood-onset dermatitis, arthritis, and uveitis, without lung involvement, treated with steroids, methotrexate, and TNF inhibitors.

Bleeding

Bleeding (hemorrhage) is blood loss from damaged vessels, arrested by hemostasis or by pressure, tourniquets, surgery, and transfusion; over 90% of pre-facility trauma deaths are from hemorrhage.

Bleeding time

Bleeding time, an in vivo test of primary hemostasis measuring how fast skin vessels stop bleeding after a standardized incision (normal 1–9 minutes); once widely used preoperatively, now obsolete, replaced by PFA-100 and clinical history.

Bleomycin/vinblastine

Bleomycin/vinblastine is a combination chemotherapy pairing of a DNA-cleaving antibiotic with a vinca alkaloid, used in regimens for germ cell tumors and Hodgkin lymphoma, including ABVD.

Bleomycin/vincristine chemotherapy regimen

The bleomycin/vincristine pairing is a two-drug combination used inside named chemotherapy regimens such as Stanford V, BEACOPP, and BACOP, principally for Hodgkin lymphoma, non-Hodgkin lymphoma, and germ cell tumors.

Blepharitis

Blepharitis, inflammation of the eyelid margins, is a common chronic eye condition. Types include anterior (staphylococcal, seborrheic), posterior (meibomian gland dysfunction), and Demodex blepharitis; treatment centers on lid hygiene.

Blepharo-cheilo-odontic syndrome

Blepharo-cheilo-odontic syndrome, also called blepharocheilodontic syndrome, is a rare autosomal dominant ectodermal dysplasia marked by eyelid malformations, cleft lip and palate, and conical teeth, caused by CDH1 or CTNND1 variants.

Blepharophimosis-intellectual disability syndrome, MKB type

Blepharophimosis-intellectual disability syndrome, MKB type (X-linked Ohdo syndrome, BMRS Maat-Kievit-Brunner type) is a rare X-linked recessive MED12 disorder in males with intellectual disability, blepharophimosis, ptosis, and coarsening triangular facies.

Blepharophimosis-intellectual disability syndrome, Ohdo type

Blepharophimosis-intellectual disability syndrome, Ohdo type (Ohdo syndrome, OMIM 249620) is an extremely rare malformation syndrome with blepharophimosis, ptosis, dental hypoplasia, hearing impairment, and intellectual disability; cause unknown, restricted to Ohdo's original 1986 patients.

Blepharophimosis-intellectual disability syndrome, SBBYS type

Blepharophimosis-intellectual disability syndrome, SBBYS type (SBBYSS, Say-Barber-Biesecker-Young-Simpson variant of Ohdo syndrome), a rare KAT6B-related disorder with mask-like facies, blepharophimosis, absent patellae, and severe intellectual disability.

Blepharophimosis-ptosis-epicanthus inversus syndrome

BPES (blepharophimosis-ptosis-epicanthus inversus syndrome), also called blepharophimosis syndrome, is a rare autosomal dominant FOXL2-related eyelid malformation with ptosis, telecanthus, and sometimes primary ovarian insufficiency.

Blepharoplasty

Blepharoplasty, or eyelid surgery, removes or repositions excess eyelid skin, muscle, and fat for cosmetic or functional reasons. Named by von Graefe in 1818; origins with Susruta; first double-eyelid surgery by Mikamo Nagai in 1896.

Blepharospasm

Blepharospasm, or benign essential blepharospasm, is an adult-onset focal dystonia causing involuntary orbicularis oculi spasms and forced eyelid closure; treated mainly with botulinum toxin injections every 3 to 4 months, with myectomy for refractory cases.

Blinatumomab

Blinatumomab (Blincyto) is a bispecific CD19-directed CD3 T-cell engager by Amgen, US-approved 2014, given as 28-day continuous IV infusions for B-cell precursor ALL, with CRS and ICANS boxed warnings.

Blind experiment

A blind experiment is a clinical research design that withholds treatment assignment from participants, care providers, or outcome assessors so expectations cannot bias results, as in double-blind drug trials.

Blind spot (vision)

Blind spot (vision), or physiological blind spot (punctum caecum), is the visual-field gap corresponding to the photoreceptor-free optic disc, about 6° × 7° at 15–16° temporal; discovered by Mariotte in 1668 and normally hidden by filling-in and the fellow eye.

Blinded randomized trial

A blinded randomized trial is a clinical trial in which chance assigns treatments and one or more parties stay unaware of assignments, minimizing bias in estimated treatment effects.

Blinding (clinical trials)

Blinding, also called masking, is the practice of keeping participants, providers, and outcome assessors unaware of treatment assignments in a randomized trial, reducing information bias.

Blindsight

Blindsight: residual visual capacity, such as detecting or locating stimuli, without perceptual awareness after primary visual cortex (V1) damage; coined by Larry Weiskrantz from patient DB studies, supported by LGN and superior colliculus-pulvinar pathways.