Diagnosing Nodular Regenerative Hyperplasia of the Liver Is Thwarted by Low Interobserver Agreement.

BACKGROUND AND AIMS: Nodular regenerative hyperplasia (NRH) of the liver is associated with several diseases and drugs. Clinical symptoms of NRH may vary from absence of symptoms to full-blown (non-cirrhotic) portal hypertension. However, diagnosing NRH is challenging. The objective of this study was to determine inter- and intraobserver agreement on the histopathologic diagnosis of NRH. METHODS: Liver specimens (n=48) previously diagnosed as NRH, were reviewed for the presence of NRH by seven pathologists without prior knowledge of the original diagnosis or clinical background. The majority of the liver specimens were from thiopurine using inflammatory bowel disease patients. Histopathologic features contributing to NRH were also assessed. Criteria for NRH were modified by consensus and subsequently validated. Interobserver agreement was evaluated by using the standard kappa index. RESULTS: After review, definite NRH, inconclusive NRH and no NRH were found in 35% (23-40%), 21% (13-27%) and 44% (38-56%), respectively (median, IQR). The median interobserver agreement for NRH was poor (κ = 0.20, IQR 0.14-0.28). The intraobserver variability on NRH ranged between 14% and 71%. After modification of the criteria and exclusion of biopsies with technical shortcomings, the interobserver agreement on the diagnosis NRH was fair (κ = 0.45). CONCLUSIONS: The interobserver agreement on the histopathologic diagnosis of NRH was poor, even when assessed by well-experienced liver pathologists. Modification of the criteria of NRH based on consensus effort and exclusion of biopsies of poor quality led to a fairly increased interobserver agreement. The main conclusion of this study is that NRH is a clinicopathologic diagnosis that cannot reliably be based on histopathology alone.

Monitoring of the repair process of surgically created lesions in equine superficial digital flexor tendons by use of computerized ultrasonography.

OBJECTIVE: To evaluate quantitative ultrasonography for objective monitoring of the healing process and prognostication of repair quality in equine superficial digital flexor (SDF) tendons. ANIMALS: 6 horses with standardized surgical lesions in SDF tendons of both forelimbs. PROCEDURES: Healing was monitored for 20 weeks after surgery by use of computerized ultrasonography. Pixels were categorized as C (intact fasciculi), B (incomplete fasciculi), E (accumulations of cells and fibrils), or N (homogenous fluid or cells). Four scars with the best quality of repair (repair group) and 4 scars with the lowest quality (inferior repair group) were identified histologically. Ratios for C, B, E, and N in both groups were compared. RESULTS: During 4 weeks after surgery, lesions increased 2- to 4-fold in length and 10-fold in volume. Until week 3 or 4, structure-related C and B ratios decreased sharply, whereas E and N ratios increased. After week 4, C and B ratios increased with gradually decreasing E and N ratios. At week 12, C and B ratios were equivalent. After week 12, C ratio increased slowly, but B ratio more rapidly. At week 20, C ratio remained constant, B ratio was substantially increased, and E and N ratios decreased. Values for the inferior repair group were most aberrant from normal. Ratios for C differed significantly between repair and inferior repair groups at weeks 16 and 18 and for B beginning at 14 weeks. CONCLUSIONS AND CLINICAL RELEVANCE: Computerized ultrasonography provided an excellent tool for objective monitoring of healing tendons in horses and reliable prognostication of repair quality.

Computerized ultrasonographic tissue characterization of equine superficial digital flexor tendons by means of stability quantification of echo patterns in contiguous transverse ultrasonographic images.

OBJECTIVE: To describe a method of computerized ultrasonographic tissue characterization that includes structures below the size limits of resolution in equine superficial digital flexor tendons. SAMPLE POPULATION: 2 damaged and 2 structurally normal superficial digital flexor tendons. PROCEDURE: Transverse ultrasonographic images were collected along the tendon long axis. Stability of echo pattern was quantified by means of variation in gray levels of each pixel in contiguous images and expressed as correlation, entropy, and waviness ratios. RESULTS: Normal young and normal old tissues were characterized by high correlation and low entropy and waviness ratios. In necrotic tissue, collapsed intratendinous septa resulted in high correlation, moderate entropy, and high waviness ratios. In early granulation tissue, complete lack of bundle formation resulted in values of zero for correlation and waviness ratios; loose connective tissue matrix resulted in a high entropy ratio. In late granulation tissue, formation of new bundles resulted in a high correlation ratio; swollen intratendinous septa and incomplete organization of connective tissue matrix were reflected in high entropy and waviness ratios. In early fibrotic tissue, rearrangement of tendon bundles resulted in a correlation ratio within reference range and a slight increase in the waviness ratio; an increase in cellularity and lack of fibrillar arrangement led to an increase in the entropy ratio. In late fibrotic and scar tissues, inferior quality of repair with almost complete lack of organization was reflected in low to moderate correlation, low waviness, and high entropy ratios. CONCLUSIONS AND CLINICAL RELEVANCE: Stability of echo patterns accurately reflects homogeneity of tendons in horses.