Case Report: Granulocytic Sarcoma of the Parotid in Chronic Myeloid Leukemia: A Case Report and Literature review

Introduction

Granulocytic sarcomas (GS) are a rare build-up of the malignant myeloid progenitor cells at an extramedullary location, often leading to an architectural distortion of the affected areas. These tumors typically accompany acute myeloid leukemia (AML) (3–8%), myelodysplastic syndrome (MDS) or myeloproliferative neoplasms (MPN) or chronic myeloid leukemia (CML) only during the blast crisis.¹ Further, GS has a predilection towards young and male patients and most common sites include lymph nodes, paraspinal area, dura, orbit, skin, soft tissues, bone, mediastinum, lungs, peritoneum, and the gastrointestinal tract.¹ Salivary gland involvement of GS is very rare, more so in case of a CML patient in chronic phase.² Here, we present an extremely rare case of GS involving the parotid gland in a previously diagnosed elderly female patient of CML in chronic phase.

Case report

A 74-year-old female of Indian ethnicity presented to the outpatient department of a tertiary care hospital in Maharashtra in January 2023, with an insidious onset swelling on the right sided angle of the mandible since the past 1 month (Figure 1). She had been diagnosed in 2020 with CML (chronic phase) and BCR-ABL1 positive, confirmed by flow cytometry and cytogenetics, for which she was initiated on oral imatinib therapy 400 mg daily (tyrosine kinase inhibitor). Otherwise, she had no known co-morbidities. The patient was a farmer, however, currently unable to work on health grounds. Further, the patient did not provide any relevant family history. Examination revealed a 2.5×2.5 cm solitary nodular mass, non-tender, firm to the touch and not fixed to underlying tissues. Her laboratory parameters, traced back from diagnosis till present episode are as mentioned in Table 1. The peripheral smear picture from the present episode is reflected in Figure 2. The fine needle aspiration cytology (FNAC) of the right parotid swelling performed under aseptic conditions revealed a microscopic picture of neoplastic population consisting of myeloblast, myelocytes, metamyelocytes, promyelocytes and polymorphs arranged diffusely (Figure 3). Thus, combined with the past history and the present episode’s peripheral smear and FNAC findings, a diagnosis of extra medullary relapse involving parotid gland in a known case of CML (chronic phase) on therapy was arrived upon for this patient. Post diagnosis, due to development of imatinib resistance, it was discontinued, and the treatment modality was changed to dasatinib 100 mg daily. On her subsequent routine follow-up, the patient has been responding well to her treatment, with the resolution of the right parotid swelling and no evidence of relapse observed, with her blood investigations near normal almost 6 months post the current visit.

Figure 1. Parotid gland swelling during local examination.

Figure 2. Peripheral smear picture in 40× (present episode).

Figure 3. FNAC of right parotid swelling in 100×.

Discussion

The salivary gland involvement of GS is an extremely rare phenomenon, especially in a patient diagnosed with CML in chronic phase.² Our literature search on PubMed with the following key-words “myeloid sarcoma,” “granulocytic sarcoma,” “chloroma,” “extramedullary myeloid tumor,” “salivary gland,” and “parotid gland,” revealed only 18 cases mentioned in 11 case reports and three retrospective reviews (Table 2).^2–15 Our search was limited to English language reports. Any report of GS originating from a lymph node without salivary gland involvement was excluded. The novelty of our case was that our patient is an elderly person with parotid involvement alone. Pertinently, she was diagnosed with CML BCR-ABL1 positive, which presents an overall clinical presentation not reported in the literature, since GS accompanies AML or CML in the blast phase. Hence, in the background of this clinical presentation, the ultrasound-guided FNAC was performed which revealed a cellular picture comprising of all myeloid lineages, different from the usual picture comprising of myeloblasts/AML-like picture seen in GS. Despite the rarity of this presentation, it was the prior and recent diagnosis of CML as well as the rapid development of the nodular parotid lesion, which raised a clinical suspicion of imatinib resistant secondary GS to BCR-ABL1 positive CML in chronic phase. Though imatinib has emerged as the front-line therapy for BCR-ABL1 positive CML, its resistance is on the rise.¹⁶ In such cases, if patient remains in chronic phase, second-generation tyrosine kinase inhibitors (TKIs) are advised¹⁷; thereby our patient was switched to dasatinib and responded well to the change in therapy.

Through this case, we wanted to highlight the need for combining strong clinical suspicion with cytological evaluation for the timely diagnosis of such rare secondary GS cases, so that appropriate treatment decisions can be undertaken, considering the improvement in prognosis with the advent of second-generation TKIs.

Consent

Written informed consent has been taken from the patient’s family for the use and publication of the patient’s data in this manuscript. As the patient found it difficult to comprehend the discussion around the consent for use of her data for scientific publication, hence she delegated her family to understand and provide consent on her behalf.