Concomitant cutaneous squamous cell carcinoma and chronic lymphocytic leukemia in a patient: The utility of <sup>18</sup>F‐FDG PET/CT in differentiation of nodal metastasis
Authors: Kerem Ozturk, Celalettin Ustun, Sobia Khaja, Faqian Li, Matthew Rischall, Zuzan Cayci
Journal: American Journal of Hematology (2018)

A 73-year-old Caucasian male presented with abdominal pain and found to have numerous bilateral cervical lymph nodes, bilateral axillary lymph nodes, and extensive mesenteric retroperitoneal lymphadenopathy. He was diagnosed with chronic lymphocytic leukemia (CLL) according to complete blood count showing absolute lymphocytosis of 5600/μL. He received short-term steroids and was then followed without therapy (watch-and wait) for 8 years until the patient noticed soreness on the right external ear that was progressively enlarging and ulcerating. A biopsy was performed and found to be consistent with squamous cell carcinoma (SCC). Computed tomography (CT) evaluation revealed innumerable lymphadenopathy throughout the neck, reaching up to 3.5 cm due to known small lymphocytic lymphoma/chronic lymphocytic leukemia (CLL/SLL). 18-Fluorodeoxyglucose positron emission tomography (18F-FDG PET/CT) scan was performed to determine which lymph node(s) if any were involved by SCC since otherwise it was not possible to differentiate the cutaneous SCC (cSCC) metastasis. On 18F-FDG PET/CT, the multiple enlarged lymph nodes of SLL/CLL demonstrated moderate FDG uptake (SUVmax of 5.3) (Image 1A,B). However, single sub-centimeter right level 2 cervical lymph node demonstrated relatively much more intense FDG uptake suspicious for metastasis from cSCC (SUVmax of 11.3) (Image 1C,D). Ultrasound-guided fine needle cytology (FNAC) was performed from the single highly FDG avid right level 2 node (suspected for metastasis from cSCC) and revealed the malignant squamous cells. In the surgery, resection of the residual skin tumor with unilateral modified radical neck dissection was performed. All submitted 25 lymph nodes were involved with SLL/CLL. Two closely adjacent right level 2 lymph nodes were positive for SCC metastases (2/25) with concurrent architectural effacement representing also the involvement by lymphoma (Image 1E-G). SLL/CLL, the most common form of chronic leukemia/lymphoma in the United States, affects mostly the elderly population.1 Patients with SLL/CLL have an increased risk of developing other malignant neoplasms. Skin cancer is the most frequently associated malignancy; among this group, SCC appears to be the predominant type of skin cancer.2 Similar to SLL/CLL, head and neck cSCC can cause nodal metastases in the cervical region. Although SLL/CLL management will not significantly be affected by the number of lymph node involvement, the presence of lymph node metastases of head and neck cSCC is a substantial prognostic determinant with direct impact on survival.3 For this reason, accurate staging of the cervical lymph node is of critical importance. Unfortunately, in patients with CLL/SLL, lymphadenopathy may be incorrectly attributed to involvement by hematological disease, precluding early/correct diagnosis and treatment of head and neck cSCC. Metastasis of cutaneous SCC and CLL/SLL in the same lymph node is a sporadic event.4 The 18F-FDG PET/CT may have clinical value in the baseline workup, especially in high-risk cSCC patients. A strategy that integrated utilization of 18F-FDG PET/CT is necessary for identification of metastatic SCC lymph nodes in the background of innumerable SLL/CLL nodes. Ethical Standards. All procedures performed were in accordance with the ethical standards of the institutional research committee and with the 1983 revised Helsinki declaration and its later amendments or comparable ethical standards. A, Numerous, pathologically enlarged and moderately FDG avid (SUVmax of 5.3) bilateral cervical lymph nodes compatible with CLL involvement on non-contrast CT and B, PET-CT fusion. C, 18F-FDG PET/CT demonstrating a markedly FDG avid (SUVmax of 11.3) right level 2 lymph node, highly suspicious for SCC metastasis and D, PET-CT fusion. E, Pathology specimen from a level 2 lymph node demonstrating adjacent areas of lymphoma (white asterisk) and squamous cell carcinoma (yellow asterisk) (hematoxylin–eosin stain; original magnification 10×); F, Squamous cell carcinoma with original magnification of specimen; G, Lymphoma with original magnification 40× [Color figure can be viewed at wileyonlinelibrary.com] All authors of this manuscript, Kerem Ozturk, Celalettin Ustun, Sobia Khaja, Faqian Li, Matthew Rischall, Zuzan Cayci declare that they have no conflict of interest.