Pathology of the spleen in hematologic disease

Splenic myeloid metaplasia in warm autoimmune hemolytic anemia (wAIHA): a retrospective study

Background

Splenic myeloid metaplasia (SMM) is a kind of extramedullary hematopoiesis, whereas its clinical significance in wAIHA remains unclear. The aim of this study is evaluating the frequency and clinical characteristics of SMM, compared with splenic-congestion (SC).

Methods

We included patients with wAIHA treated in a Mexican tertiary hospital between January 1992 and December 2015. All patients received steroids as first-line treatment and splenectomy as second-line treatment.

Results

Among the thirty-six splenectomized patients, 15 (41.6%) and 21 (58.4%) were diagnosed as SMM and SC, respectively. No differences were found in clinical characteristics between two groups. SMM patients showed lower platelet count (147×10⁹/L vs. 240×10⁹/L, P=0.02) and higher presence of anti-dsDNA antibodies (40% vs. 4.7%, P=0.01) than SC patients. Although the complete response (CR) rate with first-line treatment was lower in SMM patients (13.3% vs. 47.6%; P=0.04), post-splenectomy median disease-free-survival (DFS) was longer (16.2 mo vs. 5.1 mo; P=0.19). Univariate/multivariate analysis showed that achieving CR during first-line treatment (OR 0.3, 95% CI: 0.03–0.94, P=0.03) and higher platelet count (OR 0.99, 95% CI: 0.98–0.99, P=0.03) were protective factors for SMM; and anti-dsDNA titer higher than 9.6 IU/dL was a risk factor for SMM (OR 2.76, 95% CI: 1.48–5.14, P<0.001).

Conclusion

The wAIHA patients with SMM have different biological profiles with those without SMM. This study is the first trial evaluating the significance of histopathological spleen findings and their association with rheumatologic profile.

Spleen histology in children with sickle cell disease and hereditary spherocytosis: hints on the disease pathophysiology

Hereditary spherocytosis (HS) and sickle cell disease (SCD) are associated with splenomegaly and spleen dysfunction in pediatric patients. Scant data exist on possible correlations between spleen morphology and function in HS and SCD. This study aimed to assess the histologic and morphometric features of HS and SCD spleens, to get possible correlations with disease pathophysiology. In a large series of spleens from SCD, HS, and control patients, the following parameters were considered: (i) macroscopic features, (ii) lymphoid follicle (LF) density, (iii) presence of perifollicular marginal zones, (iv) presence of Gamna-Gandy bodies, (v) density of CD8-positive sinusoids, (vi) density of CD34-positive microvessels, (vii) presence/distribution of fibrosis and smooth muscle actin (SMA)-positive myoid cells, and (viii) density of CD68-positive macrophages. SCD and HS spleens had similar macroscopic features. SCD spleens had lower LF density and fewer marginal zones than did HS spleens and controls. SCD also showed lower CD8-positive sinusoid density, increased CD34-positive microvessel density and SMA-positive myoid cells, and higher prevalence of fibrosis and Gamna-Gandy bodies. HS had lower LF and CD8-positive sinusoid density than did controls. No significant differences were noted in red pulp macrophages. By multivariate analysis, most HS spleens clustered with controls, whereas SCD grouped separately. A multiparametric score could predict the degree of spleen changes irrespective of the underlying disease. In conclusion, SCD spleens display greater histologic effacement than HS, and SCD-related changes suggest impaired function due to vascular damage. These observations may contribute to guide the clinical management of patients.

Clinical features and splenic pathologic changes in patients with autoimmune hemolytic anemia and congenital hemolytic anemia

We characterized the pathologic changes in 50 spleens from patients with autoimmune hemolytic anemia and in 13 spleens from patients with congenital hemolytic anemia. The major pathologic findings in autoimmune hemolytic anemia were mild to pronounced cord congestion and variable white pulp area, erythrophagocytosis in conjunction with an increased polymorphonuclear neutrophil reaction, and increased deposition of hemosiderin and extramedullary hematopoiesis. In contrast, both the severity and the frequency of polymorphonuclear neutrophil reactions, deposition of hemosiderin, and extramedullary hematopoiesis were less in patients with congenital hemolytic anemia, and prominent cord congestion associated with an empty or collapsed sinus was noted in patients with hereditary spherocytosis. The activity of erythrophagocytosis in the sinus was more distinct in patients with congenital hemolytic anemia, especially those with nonspherocytic congenital hemolytic anemia, than in patients with autoimmune hemolytic anemia. These findings are consistent with the existence of different mechanisms of trapping and destruction of erythrocytes in autoimmune hemolytic anemia and congenital hemolytic anemia.

Morphologic and morphometric light and electron microscopic studies of the spleen in patients with hereditary spherocytosis and autoimmune haemolytic anaemia

With the aim of contributing to a better understanding of the haemolytic function of the spleen, a morphologic and morphometric study of this organ fixed by arterial perfusion was performed in nine patients with hereditary spherocytosis (HS), three with autoimmune haemolytic anaemia (AHA) and six with Hodgkin's disease without splenic involvement (controls). The spleen weight in HS and AHA (621 +/- 429 g, mean +/- SD) was significantly increased with respect to controls (168 +/- 36 g) (P = 0.003). In HS the red cell retention in the cords of Billroth was significantly increased (203 +/- 68 per 10(4) microns 2) with respect to the cases with AHA (93 +/- 35 per 10(4) microns 2) and to the controls (57 +/- 28 per 10(4) microns 2) (P = 0.004). In HS and AHA the number of macrophages per 10(4) microns 2 of red pulp was significantly increased (5.41 +/- 1.10 and 7.52 +/- 2.91, respectively) with respect to the controls (3.25 +/- 0.58) (P less than 0.003). There was no statistically significant difference between the number of macrophages in HS and AHA. The transmission (TEM) and scanning electron microscopy (SEM) studies demonstrated predominantly red cell retention in the cords of HS spleens, red cell phagocytosis by cordal macrophages in AHA spleens and in a lesser intensity in HS spleens, and phagocytosis of haematic corpuscles by sinus endothelial cells (SEC) in the cases of HS. These quantitative studies allow a better understanding of splenic red cell destruction in haemolytic syndromes.

The spleen: a correlative overview of normal and pathologic anatomy

The human spleen, an organ of unique anatomic and functional importance, is the largest component of the reticuloendothelial system, with direct interposition between systemic and portal circulation, and yet the morphologic correlates of its various functions remain somewhat mysterious. The contributions of transmission and scanning electron microscopy to the understanding of splenic structure have been considerable. They have helped clarify the three fundamental sites of structural alteration and specialization that are defined and discussed: 1) the white pulp with its two variable components--the lymphoid follicle and periarteriolar sheath--which, with the marginal zone of the red pulp, is the primary site of lymphoproliferative activity; 2) the cords of the red pulp, the functionally slow component of the splenic circulation, which sequester senescent or structurally altered red cells and effect their removal by means of scavenging macrophages (and which may be secondarily involved by the accumulation of platelets or certain types of leukemic cells, resulting in chronic cordal distention, or by the accumulation of collagen in fibrocongestive splenomegaly); and 3) the splenic sinuses, the unique structure of which determines that only healthy red cells with normally plastic and flexible membranes pass through to the venous circulation. Abnormal transiting cells such as sickle cells frequently clog the apertures to these sinuses. Direct arteriocapillary sinus terminations provide the anatomic basis for a fast component of the red pulp circulation, the existence of which was questioned for many years and the extent of which is still unknown in pathologic states.