Sorted By Test Name - Mayo Medical Laboratories

89366
CPOXS
61263
CPM, 12q15, for Well-Differentiated Liposarcoma/Atypical
Lipomatous Tumor, FISH
Clinical Information: The histological discrimination of well-differentiated liposarcoma/atypical
lipomatous tumor (WDL/ALT) from lipoma can be diagnostically challenging. However, standard
cytogenetic identification of ring and giant rod chromosomes strongly support the diagnosis of
WDL/ALT. These abnormal chromosomes are mainly composed of amplified sequences derived from
chromosome bands 12q13-15, and contain several amplified genes including MDM2, CPM, CDK4, and
TSPAN31. MDM2 is amplified in >99% of WDL, and up to 30% of other types of sarcomas. The CPM
gene encodes carboxypeptidase M, a membrane-bound arginine/lysine carboxypeptidase. CPM is located
only 11 kb upstream from MDM2, and is consistently coamplified with MDM2 in WDL/ALT.(1) Similar
to MDM2, this gene has been observed to be amplified in virtually all cases of WDL/ALT, but not in
lipomas.
Useful For: Supporting a diagnosis of well-differentiated liposarcoma/atypical lipomatous tumor
Interpretation: An interpretive report will be provided. A neoplastic clone is detected when the
percent of cells with an abnormality exceeds the normal reference range for the CPM FISH probe
(positive result). A positive result is consistent with amplification of the CPM gene locus on 12q13-15
and supports the diagnosis of well-differentiated liposarcoma/atypical lipomatous tumor (WDL/ALT). A
negative result is consistent with absence of amplification of the CPM gene locus on 12q13-15. However,
negative results do not exclude the diagnosis of WDL/ALT. Amplification varies in individual tumors and
among different cells in the same tumor.
Reference Values:
0-9% amplified cells
Clinical References: 1. Erickson-Johnson MR, Seys AR, Roth CW, et al: Carboxypeptidase M: a
biomarker for the discrimination of lipoma from liposarcoma. Mod Pathol 2009 Dec;22(12):1541-1547 2.
Jacob E, Erickson-Johnson MR, Wang X, et al: Assessment of MDM2 amplification using fluorescence in
situ hybridization on paraffin-embedded tissue discriminates atypical lipomatous tumors from lipomas.
Mod Pathol 2006;19:13A
CPOX Gene, Full Gene Analysis
Clinical Information: Hereditary coproporphyria (HCP) is an autosomal dominant (AD) acute
hepatic porphyria that presents with clinical attacks of neurologic dysfunction, commonly characterized as
abdominal pain. However, these acute attacks are variable and can include vomiting, diarrhea,
constipation, urinary retention, acute episodes of neuropathic symptoms, psychiatric symptoms, seizures,
respiratory paralysis, tachycardia, and hypertension. Respiratory paralysis can progress to coma and
death. HCP is also associated with cutaneous manifestations, including edema, sun-induced erythema,
acute painful photodermatitis, and urticaria. In some cases, patients present with isolated photosensitivity.
HCP is caused by AD mutations in the CPOX gene. Mutations may have incomplete penetrance.
Homozygous mutations in CPOX have been reported in association with a more severe, phenotypically
distinct condition called harderoporphyria that is characterized by neonatal hemolytic anemia with mild
residual anemia during childhood and adulthood. Affected patients may also present with skin lesions and
fecal harderoporphyin accumulation may be observed. This condition is inherited in an autosomal
recessive pattern and all patients identified to date have been heterozygous or homozygous for the K404E
mutation. For HCP, acute attacks may be prevented by avoiding both endogenous and exogenous triggers.
These triggers include porphyrogenic drugs, hormonal contraceptives, fasting, alcohol, tobacco, and
cannabis. Fecal porphyrins analysis and quantitative urinary porphyrins analysis are helpful in
distinguishing HCP from other forms of acute porphyria.
Useful For: Confirmation of hereditary coproporphyria (HCP) for patients with clinical features This
test should be ordered only for individuals with symptoms suggestive of HCP. Asymptomatic patients
with a family history of HCP should not be tested until a mutation has been identified in an affected
family member.
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