case_images: PMC11374612_01
case_images: Gross features of FPH skin nodules. Presence of nodular lesions in the muzzle area (A), lower and upper lip (B), and on the digit of the left hind limb (C).
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case_images: On physical examination, vital parameters were within normal range and the cat was otherwise healthy except for the presence of nodular, alopecic, non-ulcerated lesions in the nasal region, lower lip, digit, and two lesions on the tail, with the largest measuring 1.5 cm (Figure 1).
case_images: Histological features of FPH from the nasal planum nodule. H&E (40x objective) (A); Positive immunolabeling for Iba-1 (B) (40x objective).
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case_images: fig2
case_images: There were 12 mitotic figures in 2.37 mm2, moderate pleomorphism with occasional karyomegaly, and a discreet lymphoplasmacytic infiltrate. Only Iba-1 was positive, confirming the histiocytic origin (Figure 2).
case_images: Gross features of FPH skin nodules. Clinical presentation after the first cycle of lomustine and doxorubicin with a 14-day interval. Lesions showing slight increase in size (A) and ulceration with the presence of crust on the upper lip (B).
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case_images: fig3
case_images: TOP 3 -Agener Uniao, Brazil-500 mg, PO, SID, continuous use) were also prescribed. There was no objective response 14 days after a single dose of each chemotherapeutic agent, and the disease progressed, with increasing size and number of lesions, some nodules also became ulcerated (Figure 3).
case_images: Gross features of FPH skin nodules. Clinical presentation after 21 days of starting toceranib phosphate, demonstrating pale and dry lesions. Lesions on the muzzle (A), lips (B), and digit (C).
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case_images: fig4
case_images: After 21 days of toceranib phosphate use, the patient was reassessed, and the lesions appeared of similar size but less edematous, erythematous and exsudative (Figure 4).
case_images: Gross features of FPH skin nodules. Clinical presentation after a short term stable disease with toceranib, showing an increase in size and ulceration of the lesions. Lesions on the muzzle (A, B), lips (A, B), right upper eyelid (B), and digit (C).
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case_images: fig5
case_images: At the subsequent follow-up, after broadly 6 weeks of stable disease there was a significant progression of the lesions in the nasal region, along with ulceration of the cutaneous lesions (Figure 5) and an increase in size of the left popliteal lymph node.
case_images: FPH cytology, Diff Quick staining. Retropharyngeal lymph node sample. Background with moderate red blood cells numbers. High large histiocytic cells, moderate small lymphocytes and low neutrophils numbers (10x objective) (A). Retropharyngeal lymph node sample. Histiocytic cells have a moderate nucleus-to-cytoplasm ratio, rounded or oval nucleus, moderate anisokaryosis, single nucleolus and low to moderate basophilic cytoplasm (red arrow). Presence of cytophagocytosis (blue arrow). The small lymphocytes present typical morphology (arrowhead) (40x objective) (B). Retropharyngeal lymph node. Multinucleated histiocytic cell (arrow) and mitotic figure (arrowhead) (40x objective) (C). Popliteal lymph node sample. Presence of high small lymphocytes (arrowhead) and a low histiocytic cells numbers, with the last ones exhibiting the same pattern observed in the retropharyngeal lymph node sample (red arrow) (40x objective) (D). Superficial cervical lymph node. Background with high red blood cells numbers. Presence of large histiocytic cells, showing high anisokaryosis (red arrow), binucleated cells (blue arrow) and mitotic figures (arrowhead) (10x objective) (E). Superficial cervical lymph node sample. Histiocytic cells with a prominent single nucleolus, binucleation with cytophagocytosis (blue arrow) and multinucleation (red arrow) (40x objective) (F).
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case_images: fig6
case_images: The lymph node underwent fine-needle aspiration cytology (FNAC), confirming the FPH involvement of the popliteal lymph node (Figure 6D). The cytology described the abundant presence of histiocytes, oval to spindle-shaped, with low to variable nucleus-to-cytoplasm ratio, oval nuclei, intense anisocytosis, coarse chromatin pattern, single and inconspicuous nucleoli, discretely basophilic and poorly demarcated cytoplasm, mild to moderate presence of binucleated cells and large cells, as well as cytophagocytosis and erythrophagocytosis, with more than 5 mitotic figures per field (Figures 6A-C). Multivacuolated nuclei, figures of cytophagocytosis and multinucleation, as well as atypical mitotic figures, were observed, favoring a suggestive diagnosis of HS (Figures 6E,F).
case_images: Gross features of FPH skin nodules. Clinical presentation 18 days after the third ECT session. Presence of crusts between the nasal planum and upper lip and vibrissal region (A), dorsum (B), and fourth digit (C), sites of ECT application in the healing process.
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case_images: fig7
case_images: After 18 days from the third session, there was 80% of reduction in size of the nodules (Figure 7).
case_images: Gross features of FPH skin nodules. Patient in complete remission with treatment involving toceranib phosphate, chlorambucil, and 3 months after the sixth ECT session. Scar on the nose with exposure of nasal mucosa.
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case_images: fig8
case_images: After completing 6 ECT sessions, 200 days from the start of toceranib phosphate, and 114 days from the combination of toceranib phosphate and chlorambucil, there was complete remission of the cutaneos lesions observed (Figure 8) and there was no abnormalities on physical examination, abdominal ultrasound and thoracic radiographs.