Pilomatricoma, is a benign skin tumor derived from the hair matrix. These neoplasms are relatively uncommon and typically occur on the scalp, face, and upper extremities. Clinically, pilomatricomas present as a subcutaneous nodule or cyst with unremarkable overlying epidermis that can range in size from 0.5 to 3.0 cm, but the largest reported case was 24 cm. Presentation
Associations
Pilomatricomas have been observed in a variety of genetic disorders including Turner syndrome, myotonic dystrophy, Rubinstein-Taybi syndrome, Trisomy 9, and Gardner syndrome. It has been reported that the prevalence of pilomatricomas in Turner syndrome is 2.6%.Hybrid cysts that are composed of epidermal inclusion cysts and pilomatricoma-like changes have been repeatedly observed in Gardner syndrome. This association has prognostic import, since cutaneous findings in children with Gardner Syndrome generally precede colonic polyposis. Histologic features
The characteristic components of a pilomatricoma include a stroma of fibrovascular connective tissue
surrounding irregularly shaped, lobulated islands containing basaloid cells (being darkly stained, round or elongated, with indistinct cell borders and minimal cytoplasm, with nuclei being round to ovoid, deeply basophilic and generally prominent nucleoli), which abruptly or gradually transitions into ghost cells (having abundant, pale, eosinophilic cytoplasm, well defined cell borders and a central clear area, but only faint traces of nuclear material), which in turn may transition into keratinaceous to amorphous necrosis.The presence of calcifications with foreign body giant cells is common within the tumors. Pathogenesis
Pilomatricoma is associated with high levels of beta-catenin caused by either a mutation in the APC gene or a stabilizing mutation in the beta-catenin gene, CTNNB1.
Clinical pharmacology
As is evident with the parent molecule, atracurium, cisatracurium is also susceptible to degradation by Hofmann elimination and ester hydrolysis as components of the in vivo metabolic processes. See the atracurium page for information on Hofmann elimination in vivo versus the Hofmann degradation chemical reaction. Because Hofmann elimination is a temperature- and plasma pH-dependent process, cisatracuriums rate of degradation in vivo is highly influenced by body pH and temperature just as it is with the parent molecule, atracurium: thus, an increase in body pH favors the elimination process, whereas a decrease in temperature slows down the process. One of the metabolites of cisatracurium via Hofmann elimination is laudanosine – see the atracurium page for further discussion of the issue regarding this metabolite. 80% of cisatracurium is metabolized eventually to laudanosine and 20% is metabolized hepatically or excreted renally. 10-15% of the dose is excreted unchanged in the urine.Since Hofmann elimination is an organ-independent chemodegradative mechanism, there is little or no risk to the use of cisatracurium in patients with liver or renal disease when compared with other neuromuscular-blocking agents.The two reverse ester linkages in the bridge between the two isoquinolinium groups make atracurium and cisatracurium poor targets for plasma cholinesterase, unlike mivacurium which has two conventional ester linkages. Adverse effects
Histamine release – hypotension, reflex tachycardia and cutaneous flush
Bronchospasm – Pulmonary compliance
To date, cisatracurium has not been reported to elicit bronchospasm at doses that are clinically prescribed.