Table 5

 Histomorphological diagnostic features to consider

Tissue/HistopathologyConsider in diagnosis
Endocardium
    FibrosisOrganised thrombus
Healed biopsy site
Myocardial infarct
Healed acute rejection site
Graft procurement injury
Adjacent prosthetic device
Abnormal blood flow haemodynamics
Hypereosinophilic syndrome
Mastocytosis
Endocardial fibroelastosis
Healed myocarditis
Cardiomyopathy
Drug toxicity
    Ulceration/necrosisAdjacent prosthetic device
Healing biopsy site
Hypereosinophilic syndrome
Myocardium
    HypertrophyHypertrophic/dilated cardiomyopathy
Pressure/volume overloaded ventricle
Storage disorders
Primary myopathies (Duchenne’s/Becker’s)
Muscular dystrophies (myotonic)
    Fibre disarrayHypertrophic cardiomyopathy
Healed biopsy site
Ventricular apex
Junction of free wall and interventricular septum
Interstitium
    FibrosisHealed biopsy site
Myocardial infarct
Healed acute rejection site
Adjacent prosthetic device
Hypereosinophilic syndrome
Mastocytosis
Healed myocarditis
Cardiomyopathy
Drug toxicity
    LymphocytesAllograft rejection (focal or diffuse)
Quilty lesion (A or B)
Normal allograft (sparse and diffuse)
Myocarditis/dilated cardiomyopathy
Post transplant lymphoproliferative disease
Lymphoma
Leukaemia
    NeutrophilsBacterial/fungal endocarditis (±necrosis)
Fulminant acute allograft rejection
Fulminant myocarditis
Hypereosinophilic syndrome (+eosinophils)
Sepsis
    EosinophilsHypereosinophilic syndrome (Loeffler’s)
Hypersensitivity (for example, drug)
Fulminant allograft rejection
Parasitic infection (Chagas)
    GranulomasSarcoidosis
Amyloidosis
Aschoff nodules
Foreign body reaction
Giant cell myocarditis
Intramural vessel changes Allograft vasculopathy
Hypertrophic cardiomyopathy
Systemic arterial hypertension
Amyloidosis
Collagen vascular disorders
Mitral valve prolapse