case_images: PMC10716452_01
case_images: Histologic features of ALK-positive histiocytosis. (A) Breast biopsy with 100X hematoxylin and eosin staining showing the contrast between normal breast tissues on the left and APH on the right, which consists of sheets of packed proliferating cells with eosinophilic cytoplasm. (B) Immunohistochemistry staining showing positive ALK1 expression. (C) 400X H&E staining shows foamy histiocytes with irregularly folded or lobulated nuclei. (D) Lung biopsy with 100X H&E staining showed similar histologic findings of APH.
case_images: fmed-10-1288849-g0001.jpg
case_images: PMC10716452_01_fmed-10-1288849-g0001.jpg
case_images: F1
case_images: Immunohistochemistry stains (IHC) were positive for ALK1, CD163, CD68, and S100 and negative for HMWK, cytokeratin, p63, CD34, desmin, actin, STAT6, SOX10, AFB, and GMS (Figure 1). According to the clinical presentations, histology, immunophenotyping, and genetic workup, this case confirmed a diagnosis of ALK-positive histiocytosis (Figures 1, 2).
case_images: Radiologic features of APH and case timeline. (A) CT scan of the chest with contrast before (A i) and after (A ii) starting crizotinib. Near-complete resolution of the right-side breast mass and left lung nodule are shown. (B) MRI of the brain before (B i) and after (B ii) crizotinib treatment, showing a complete response of the right caudate head lesion. (C) MRI of the spine at initial presentation showing soft disease involvement at the right C3-4 foramen. (D) MRI of the brain showing the calvarial lesion in the posterior left parietal bone at the vertex before treatment. (E) A clinical, diagnostic, and treatment timeline.
case_images: fmed-10-1288849-g0002.jpg
case_images: PMC10716452_01_fmed-10-1288849-g0002.jpg
case_images: F2
case_images: The results indicated that the patient suffered from extensive metastasis, with numerous lung nodules (the largest measuring 9 mm), multiple small brain intra-axial enhancing nodules, parietal bone lesions, multiple parotid nodules, and a dumbbell-shaped soft tissue mass at the right C3-4 foramen, without any lesions in her liver (Figure 2). According to the clinical presentations, histology, immunophenotyping, and genetic workup, this case confirmed a diagnosis of ALK-positive histiocytosis (Figures 1, 2). A follow-up CT scan 4 months after treatment initiation showed complete resolution of her lung, breast, brain, and bone diseases (Figure 2). A timeline of her clinical presentation, diagnostic journey, and treatment initiation is illustrated in Figure 2E.