PMC7686237_01
In a 13-months old girls, bilateral severe pulmonary dystelectasis, revealed by post-mortem examination (A), correspond to the Rx-image, which shows ground-glass opacities, in the right lung, and diffuse opacity of the left lung (B).
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F1
A chest X-ray revealed almost complete opacity in the left lung and patchy infiltrates in the right lung (Figure 1). Both lungs were enlarged, firm, and dystelectatic (136 g left; 169 g right) and without friable areas; the cut section was without gross features suggestive of bronchopneumonia (Figure 1).
Microscopic and immunohistochemical features of desquamative interstitial pneumonia: (A) hemorrhages and thrombi (arrow); (B) bronchiolar damage; (C) desquamated pneumocytes, with syncytial-like bodies; (D) scanty T-cells; (E) necrosis of the desquamated cells, with genesis of membranes; (F) Encasement of alveolar septa by cytokeratin-positive membranes; (G) Positivity of the desquamated cells for cytokeratin; (H) IgA positivity in the desquamated cells.
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F2
Under a microscope, the pulmonary sample examination showed bilateral diffuse alveolar damage (DAD) with severe desquamation of type II alveolocytes (pneumocytes) and the presence of intra-alveolar macrophages (Figure 2). Small foci of extravasated erythrocytes were also described along with vascular thrombi (Figure 2). Inside the alveoli, few neutrophils were in the neighboring membranes (Figures 2, 3).
Stepwise genesis of hyaline-membrane-like structures, in desquamative interstitial pneumonia (DIP).
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F3
A particular aspect regarded the possible stepwise formation of hyaline membranes from CD68/CK-positive desquamated pneumocytes (Figure 3). Inside the alveoli, few neutrophils were in the neighboring membranes (Figures 2, 3).
Gross and microscopic features of liver and spleen. (A-C) Liver centrilobular fatty change, with pale macro- (A) and microscopic area (B), which show a multivacuolar aspect, at high power view (C), being marked by *; (D-F) Splenomegaly specimen (D) is characterized by enlargement of the white pulp (E), with T cell-rich aspect of the red pulp (F), proved by the CD3 positivity (F corner).
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F4
T cell infiltration of the red pulp was described (Figure 4). T-cell hyperplasia of the paracortical area was also observed in the pericecal mesenteric lymphadenopathies.
Gross findings of kidneys. (A) Bilateral enlargement, with hyperaemic surface of the left kidney; (B,C) Passive hyperemia of the cortex; (C,D) Parenchymatous congestion, with interstitial edema.
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F5
Macroscopically, the left kidney was clearly hyperemic with a predominance of cortex hyperemia on the cut section (Figure 5). The macroscopically hyperemic cortex showed dilatation of the veins under microscope (Figure 5), which might be the effect of blood flow impairment.
Proliferative glomerulonephritis. In Hematoxylin-Eosin, microscopic features consist on mesangium enlargement and proliferation of podocytes (A-C). Immunohistochemically, the proliferated podocytes are marked by WT1 (D) and surround the CD31-positive capillaries (E), without positivity for CD44 (F).
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F6
IgA-positive cells and the proliferation of WT1-positive podocytes, without modifications to the cells of Bowman's capsule; this fact was confirmed by negative staining for CD44 (Figure 6). Interstitial nephritis with mononuclear cells was also described.