PMC8016594_01
Hematoxylin and eosin (H&E) and immunohistochemical (IHC) staining. (a) H&E of needle core biopsy at low power showing aggregates of Langerhans cells surrounded by small mature lymphocytes. (b) H&E of LCH cells with oval nuclei showing features of nuclear grooves, occasional binucleation, and abundant cytoplasm without granules. (c) IHC for CD1a showing strong diffuse cytoplasmic staining with membranous accentuation. (d) IHC for S-100 showing variable strong to weak cytoplasmic staining.
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US-guided biopsy demonstrated LCH cells with oval nuclei showing features of nuclear grooves, occasional binucleation, and abundant cytoplasm without granules as well as strong diffuse cytoplasmic staining for CD1a and variable weak to strong cytoplasmic staining for S-100 (Figure 1).
PET/CT imaging prior to starting radiotherapy. Axial CT of patient axilla (arrows) (a) and corresponding PET image (b). Axial CT of patient's right popliteal mass (arrow) (c) and corresponding PET image (d).
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The decision to continue therapy was made, and end of therapy PET/CT imaging demonstrated a mixed metabolic response to treatment with persistent avidity demonstrated in the previously described regions, including the right popliteal (Figure 2).
(a) Right axillary lesions 3 weeks after RT (8 Gy in 1 fraction). (b) Left axillary lesions prior to RT. Clinical response following RT for the right axilla (5-month posttreatment) (c) and left axilla (4-month posttreatment) (d).
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At that time, he described an improvement in pain and discharge of the treated skin lesions (Figure 3(a)). However, his left axilla was becoming more bothersome (Figure 3(b)) and it showed similar ulcerative lesions with associated discharge. The patient was seen in follow-up 4 months after completing his last fraction of RT with no evidence of disease in his left axilla (Figure 3(d)). By comparison, the right axilla had stable residual disease (Figure 3(c)).
PET/CT imaging approximately 7 months after starting RT. Axial CT of patient axilla (arrows) (a) and corresponding PET image (b). Axial CT of patient's right popliteal mass (arrow) (c) and corresponding PET image (d).
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The patient continued to follow with medical oncology, and PET/CT obtained (7 months after RT, 5 months duration of vemurafenib) revealed complete metabolic response of the axilla (Figures 4(a) and 4(b)) and stable mixed response in the popliteal region (Figures 4(c) and 4(d)).