| Abstract|| |
Myeloid sarcoma (MS) is an extramedullary proliferation of immature myeloid cells which may occur as a progression of myelodysplastic syndrome (MDS), myeloproliferative neoplasm (MPN), or myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) and as acute myeloid leukemia (AML) relapse. Rarely may it be de novo. Lymph nodes, skin, lungs, intestine are the commonly involved sites. However, an isolated pancreatic MS is seldom reported in the literature. Herein, we report one such case which was misdiagnosed as pancreatic adenocarcinoma on the clinico-radiological examination which misled us away from preoperative diagnostic sampling, and a Whipple pancreaticoduodenectomy was performed. Histopathological examination in conjunction with immunohistochemistry revealed the final diagnosis of isolated MS of the pancreas. We emphasize that although rare, a clinical suspicion along with preoperative histopathological examination may lead to early diagnosis, targeted management, and a better clinical outcome in such cases.
Keywords: Chloroma, granulocytic sarcoma, myeloid sarcoma, pancreatic malignancy
|How to cite this article:|
Soni A, Jindal S, Narang V, Singh A, Paul D, Kaur H. Isolated pancreatic myeloid sarcoma: A potential mimicker of pancreatic adenocarcinoma. Indian J Pathol Microbiol 2022;65:676-8
|How to cite this URL:|
Soni A, Jindal S, Narang V, Singh A, Paul D, Kaur H. Isolated pancreatic myeloid sarcoma: A potential mimicker of pancreatic adenocarcinoma. Indian J Pathol Microbiol [serial online] 2022 [cited 2022 Aug 15];65:676-8. Available from: https://www.ijpmonline.org/text.asp?2022/65/3/676/351596
| Introduction|| |
Myeloid sarcoma (MS) is classified under acute myeloid leukemia and related precursor neoplasms by WHO and is defined as presence of solid masses of myeloid blast with or without maturation at anatomical sites other than bone marrow. The pathogenesis is unclear; it may occur in association with other myeloid neoplasms, as relapse in AML cases or infrequently de novo. Isolated MS is a rare affair with an incidence rate of approximately 2 per 1,000,000 individuals. Isolated MS of the pancreas is seldom described in literature. We report a unique case of isolated pancreatic MS in a 60-year-old female who presented with symptoms of obstructive biliopathy. The clinico-radiological examination was misleading and a final diagnosis could only be made by histopathology and immunohistochemistry (IHC).
| Case Report|| |
A 60-year-old female presented with abdominal pain of ten months duration. She also complained of jaundice which was progressively worsening. General physical examination revealed pallor and icterus with vitals being within normal limits. Complete blood count showed hemoglobin - 9.9 gm/dl; total leukocyte count - 8.0 × 10^3/μl and platelet count- 158 × 10^3/μl. Peripheral blood film showed a normocytic normochromic blood picture with no immature cells. Liver function tests revealed hyperbilirubinemia (total - 5.99 mg/dl & direct - 5.77 mg/dl) with raised liver enzymes (SGOT - 142μ/l, SGPT - 207μ/l & ALP - 201μ/l). Renal function tests were within normal limits. Blood amylase level was normal (53.0 U/L) ruling out the possibility of pancreatitis. Abdominal computed tomography (CT) revealed a poorly marginated heterogeneously enhancing soft tissue lesion in the uncinate process and head of the pancreas measuring 2.5 × 2.9 cm leading onto obstructing biliopathy. A radiological possibility of this being a pancreatic adenocarcinoma was rendered. Pancreaticoduodenectomy (Whipple procedure) was carried out for symptom management, mass resection, and final diagnosis on histopathology. Grossly, a thickened ill-defined area was identified in the head of the pancreas measuring 2 × 1 × 1 cm. Histopathological examination revealed diffuse sheets of small to medium-sized atypical cells infiltrating in a streak-like pattern into the adjacent pancreas ([Figure 1]; panel A) and the wall of duodenum, having conspicuous nucleoli and moderate amount of basophilic cytoplasm ([Figure 1]; panel B). On Immunohistochemistry (IHC) the tumor cells expressed positivity for CD117 ([Figure 1]; panel C), CD99 ([Figure 1]; panel D), and CD68 ([Figure 1]; panel E) with a Ki-67 proliferation index of 30%. The cells showed immunonegetivity for cytokeratin, CD3, CD20, CD138, Cyclin D1, synaptophysin, chromogranin, and CD34. Bone marrow examination did not show involvement by tumor. Thus, a final diagnosis of isolated myeloid sarcoma of the pancreas was rendered. The patient was started on chemotherapy and is on a regular clinical follow up.
|Figure 1: Photomicrograph (H & E; ×40; panel A) shows sheets of myeloblasts infiltrating the pancreas in streak-like pattern. Photomicrograph (H & E; ×400; panel B) shows small to medium sized neoplastic myeloid cells exhibiting conspicuous nucleoli and moderate cytoplasm. Photomicrograph shows neoplastic myeloid cells exhibiting immunopositivity for CD117 (panel C), CD99 (panel D), and CD68 (panel E)|
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| Discussion|| |
Myeloid sarcoma (also called granulocytic sarcoma or chloroma) is defined as presence of solid masses of myeloid blast with or without maturation at anatomical sites other than bone marrow. It is most commonly seen in association with AML, either simultaneously or following the onset of AML, and sometimes occurs as a progression of other hematological neoplasm like MPN, MDS, or MDS/MPN. Isolated MS is defined as MS occurring in absence of any other hematological neoplasm and no marrow involvement at the onset of disease. It is an extremely uncommon entity with an incidence rate of <1%. Although it has been listed separately in WHO classification, a comprehensive investigation panel is warranted to classify it into a more specific AML subtype.
Commonly involved sites are lymph nodes, skin, lungs, intestine, etc. However, only a handful of isolated pancreatic MS cases have been reported in the literature till date. To the best of our knowledge, this is the ninth case of isolated pancreatic MS in absence of concurrent hematological neoplasm.
The symptomatology of MS is related to tumor mass effect and is very non-specific. Thus, the diagnosis of isolated MS is quite challenging and is missed at the time of initial diagnostic workup with a misdiagnosis rate being as high as 75%. Patients with pancreatic MS may be asymptomatic or present with pain abdomen and/or obstructive biliopathy, as noted in our case too. On magnetic resonance imaging (MRI), MS appears as hypointense lesions on T1-weighted images and more isointense lesions on T2-weighted images. On contrast-enhanced computed tomography (CECT) it shows moderate contrast enhancement. However, none of these findings is specific for MS and can also be seen in other conditions like abscess, lymphoma, etc. There is no established serum tumor marker for MS which further adds to diagnostic difficulties. Hence, unless having suspected clinically it is nearly impossible to diagnose isolated MS on clinical and radiological grounds alone. In our case, an imaging diagnosis of suspected pancreatic adenocarcinoma with a resectable mass on radiology misled us away from the preoperative diagnostic sampling and a curative pancreaticoduodenectomy was performed. Histopathological examination (HPE) along with IHC confirmed the final diagnosis of MS. A preoperative sampling like tru-cut biopsy and fine-needle aspiration cytology (FNAC) may perhaps have established the diagnosis of MS in our case leading to the timely introduction of chemotherapy and avoidance of unnecessary surgical intervention.
Thus, HPE with IHC remains the gold standard diagnostic modality for isolated MS. Histopathological examination reveals sheets of myeloblasts with granulocytic or monocytic differentiation causing partial to total effacement of tissue architecture. On IHC, immunopositivity for ≥1 myeloid associated antigen is required for the diagnosis of MS (CD68, MPO, CD43, CD45, CD117, CD99, CD33, CD34, and CD13). Immunostaining for lymphoid markers (CD3 and CD20) is negative. However, rarely aberrant expression of these may be witnessed.
As per National Comprehensive Cancer Network guidelines, the treatment of choice for MS (both isolated and with marrow involvement) is induction chemotherapy which is similar to overt AML. Even though the isolated pancreatic MS lesions are surgically resectable, it is mandatory to administer the induction chemotherapy to reduce the chances of progression to over AML.
| Conclusion|| |
Isolated MS of the pancreas is an extremely rare and distressful condition. A timely diagnosis of MS in absence of marrow involvement is a huge diagnostic challenge. Yet, a clinical suspicion along with preoperative diagnostic sampling including FNAC and tru-cut biopsy with IHC may contribute to timely diagnosis, avoidance of unnecessary surgery, and a better prognosis.
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The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
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Dayanand Medical College and Hospital, Tagore Nagar, Ludhiana - 141 001, Punjab
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