ACTA CYTOLOGICA 2012;56:325-329

DYSPLASTIC MEGAKARYOCYTES AND EOSINOPHILIC PRECURSORS IN THE DIAGNOSIS OF MYELOID SARCOMA ON LYMPH NODE FINE-NEEDLE ASPIRATION CYTOLOGY

Dr. Saurav Singh

INTRODUCTION

Myeloid sarcoma is a rare manifestation characterized by the occurrence of 1 or more tumorous myeloid masses at an extramedullary site.

It is also known as extramedullary acute myeloid leukemia (AML), extramedullary myeloid tumor, myeloblastoma, granulocytic sarcoma or chloroma.

Myeloid precursors on fine-needle aspiration can be seen in a variety of pathological states, both neoplastic and non-neoplastic.

Myeloid sarcoma can precede, occur concurrently, or arise subsequent to the diagnosis of AML.

It can also arise in patients with myelodysplastic syndrome, chronic myeloproliferative disease and myelodysplastic disease.

The incidence of myeloid sarcoma ranges from 1 to 3%.

The most common sites of myeloid sarcoma are the subperiosteal bone structures of the skull, paranasal sinuses, bones, lymph nodes, and skin.

Less common sites are central nervous system, spinal cord, breast, heart, thymus, liver, spleen, pancreas, endocrine glands and female genital tracts.

Myeloid sarcoma occurs in patients with AML in three clinical settings:

1) Most often, myeloid sarcoma is associated with concurrent evidence of AML involving the blood and bone marrow.

2) Myeloid sarcoma can arise in patients with a history of AML as a sign of relapse.

3) Least frequently, myeloid sarcoma can arise in patients without a history or concurrent evidence of AML.

Myeloid sarcoma can show unilineage or multilineage proliferation and is further sub classified within the WHO scheme as differentiated, immature, and blastic.

Differentiated tumors are composed of numerous promyelocytes and more mature granulocytic cells.

Immature tumors are composed of myeloblasts, promyelocyte and blastic tumors which is least mature.

They are composed predominantly of myeloblasts with little evidence of granulocytic differentiation.

Proliferation of the erythroid or megakaryocytic series can also be seen in myeloid sarcoma, most often in cases with chronic myeloproliferative disease or myelodysplastic syndrome.

Megakaryocytes may be dysplastic, small or abnormally large in size with hyper or hypolobated nuclei, or show hyperchromasia.

Thus, the presence of immature myeloid cells, eosinophilic precursors or dysplastic megakaryocytes is supportive of the neoplastic nature of a myeloid proliferation.

MATERIALS AND METHODS During the course of study nearly 4186 FNAC of lymph

nodes were performed.

186 were diagnosed as hematolymphoid malignancies of which 15 cases were diagnosed as myeloid sarcoma with the involvement of lymph node in 10 cases.

FNAC was performed using 23- gauge disposable needle and 10 ml disposable syringe. Both non-aspiration and aspiration techniques were used.

Peripheral smears of all cases were made by using finger prick technique and stained with Giemsa stain.

RESULTS

The differentiation of granulocytic sarcoma from malignant lymphomas and other small round cell tumors is very critical.

Location of Extramedullary Proliferation: In this, 7 patients presented with multiple

lymphadenopathy and 3 patients with enlargement of a single group of lymph nodes.

The majority of the patients (8 cases) presented with cervical lymphadenopathy and 6 of these also showed inguinal and axillary lymphadenopathy.

One case had isolated inguinal lymphadenopathy and the other had multiple lymph nodes involving inguinal, axillary, pre and para -aortic groups.

CLINICAL PRESENTATION

Four patients were less than 20 years of age,3 were in the age group of 21-40, 2 were between 41 and 60 and 1 was more than 60 years of age.

The male: female ratio was 2:1.

Six patient had fever at the time of presentation,4 had hepatosplenomegaly of moderate grade,4 had symptoms related to anemia, 1 patient had skin lesions and 1 had gum bleeding.

Pre- FNAC diagnosis of a neoplastic process was present in only 2 cases (1 case of AML and 1 of CML).

In all other cases, diagnosis was confirmed by examination of peripheral smear, bone marrow examination, flow cytometry or cytogenetics.

LABORATORY FINDINGS

Complete Blood count and Peripheral Blood Smear Total white blood cell count was raised in 8 cases,

normal in 1 case and decreased in 1 case. Peripheral blood smears of all patients were taken and

stained with Giemsa stain. Eight cases showed the presence of blasts or myeloid

precursors in the peripheral blood. Three of the 8 cases showed an AML –like picture with

blasts> 20% and 4 cases showed features of CMPD with immature myeloid precursors, eosinophils and eosinophilic precursors, occasional basophils and blasts < 10%.

One case showed atypical monocytoid cells without cytoplasmic granularity on PBS.

FNAC FINDINGS: Cytological findings that suggested the diagnosis

were:

1. The presence of immature myeloid series cells, especially eosinophilic precursors.

2. Blasts with cytoplasmic granularity.

3. Dysplastic megakaryocytes.

Megakaryocytes with dysplastic forms were seen in 5 of the10 cases(2 CML, 1 AML and 2 cases where PBS do not show blast) and in conjugation with eosinophilic precursors helped in the diagnosis of myeloid sarcoma.

FOLLOW- UP In this study, there were 10 patients where myeloid

precursors were seen on fine- needle aspiration of lymph nodes and were diagnosed as myeloid sarcoma.

On further investigations, 3 cases were diagnosed as CML on PBS.

1 case was diagnosed as juvenile myelomonocytic leukemia, as the LAP(leukocyte alkaline phosphatase) score was 18 (normal range 20-180) and the Philadelphia chromosome was negative; 2 cases did not show lasts on PBS, however one of them was diagnosed as MPD on bone marrow aspirate.

DISCUSSION Myeloid sarcoma of the lymph node is an uncommon

entity and should be distinguished from myeloid metaplasia and Non- Hodgkin lymphoma.

Extramedullary hematopoiesis (EMH) or myeloid metaplasia can occur in the lymph nodes of children with benign hematological disorders like:

Thalassemia Hereditary spherocytosis Sickle cell anemia Congenital dys-erythroblastic anemia Immature thrombocytopenic purpura

Extramedullary hematopoiesis can show either unilineage or multineage proliferation like myeloid sarcoma.

The presence of myeloid precursors including blasts, eosinophilic precursors and dysplastic megakaryocytes is not seen with extramedullary hematopoiesis.

This favors a diagnosis of myeloid sarcoma over extramedullary hematopoiesis.

Myeloid sarcoma can closely resemble diffuse large cell lymphomas of B cell or T cell lineage and without clinical history and high index of suspicion are likely to be misdiagnosed.

Cytologically, diffuse large B cell lymphoma have one or more prominent nucleoli and thick nuclear membranes.

Myeloid sarcomas have eosinophilic myelocytes or other myeloid precursors which differentiate it from non-Hodgkin lymphoma.

Blasts in myeloid sarcoma also show cytoplasmic granularity which is absent in non- Hodgkin lymphoma.

In the study, 1 case which showed atypical monocytoid cells and eosinophilic precursors on FNAC was diagnosed on flow cytometry as pre-T ALL.

Pre-T ALL is usually infiltrated by eosinophils and some of these cases have developed AML, MDS or myeloid sarcoma, suggesting that both neoplasm arise from common progenitor cell.

Two cases had a normal PBS, but the presence of eosinophilic precursors and dysplatic megakaryocytes in both of them favors a diagnosis of myeloid sarcoma over extramedullay hematopoiesis.

However, myeloid sarcoma can precede diagnosis of AML or other MPD.

Thus, the presence of eosinophilic myeloid precursors and dysplastic megakaryocytes in aspirates should suggest a diagnosis of myeloid sarcoma, even in the absence of a documented myeloproliferative disease.

ACTA CYTOLOGICA 2012;56:228-232

FINE NEEDLE ASPIRATE OF AUTOIMMUNE PANCREATITIS (LYMPHOPLASMACYTIC SCLEROSING PANCREATITIS): CYTOMORPHOLOGIC CHARACTERISTICS AND CLINICAL CORRELATES

INTRODUCTION Autoimmune pancreatitis (AIP) is an inflammatory

disease of the pancreas characterized by a duct-centric lymphoplasmacytic infiltrate and fibrosis.

It is a benign condition that is often treated by nonsurgical methods such as corticosteroid therapy.

Patients with autoimmune pancreatitis have elevated level of serum IgG4 which can aid in the preoperative diagnosis of the disease.

AIP commonly presents with obstructive jaundice or weight loss.

It can form a mass-like lesion in the head of the pancreas.

AIP and ductal adenocarcinoma is challenging in the absence of a tissue diagnosis.

MATERIALS AND METHODS Case Selection:• The search criteria ‘autoimmune pancreatitis’ and ‘

lymphoplasmacytic sclerosing pancreatitis’ were used to identify surgical pancreatic specimens.

• Following clinical and pathologic data were collected for each case.

Age, gender, ethinicity, presenting symptoms , date and results of preoperative imaging studies, including radiographic impression of a mass and biliary cytology.

CYTOPATHOLOGY Material was obtained by transabdominal ultrasound

or endoscopic ultrasound-guided FNA.

Direct smears were prepared and stained with Diff Quick as well as wet-fixed for Papanicolaou staining.

The cytologic criteria used to define ductal atypia included the presence of nuclear abnormalities such as:

Hyperchromasia Irregular nuclear borders An increased nuclear-to-cytoplasmic ratio Architectural abnormalities such as the presence of

disorganization within tissue fragments.

SURGICAL PATHOLOGY Specimens were processed using standard methods

and stained with hematoxylin and eosin.

Based on the diagnosis determined at the time of original evaluation, the surgical and cytopathologic data were collected.

The results of IgG4 immunolabeling were available for 10 surgical cases.

IgG4 immunolabeling was performed on a Ventana XT benchmark automated stainer.

Antigen retrieval was done using enzyme Protease 1 for 8 min.

Incubation with mouse anti-human IgG4 was performed for 8 min at room temperature followed by an amplification step.

Hematoxylin counterstain was applied to all sections before dehydration.

A surgical specimen was determined to have increased IgG4–positive plasma cells if > 10 IgG4- positive cells were present per high power field.

RESULTS

A total of 20 FNAs from 17 patients were identified.

Fifteen patients were diagnosed with AIP based on examination of a surgical resection specimen.

Two were diagnosed by a combination of clinical history.

The surgical resections included eight Whipple resections, four distal pancreatectomies, four surgical biopsies and one Frey procedure.

Of the 10 aspirates diagnosed as atypical ,the majority were described as having rare, focal, or scattered atypical ductal cells while 1 was suspicious for malignancy, 1 could not exclude a neuroendocrine neoplasm, and 1 was makedly atypical.

Common findings included hypocellularity with a smear background lacking red blood cells.

Rare, oval-shaped fibroblastic nuclei or fragments of fibrous tissue were identified.

Seven of the 20 pancreatic FNA were accompanied by separate biliary cytology.

Of these specimens, one was diagnosed as markedly atypical and suspicious for malignancy.

IHC labeling for IgG4 was performed on the surgical specimens.

9 out of 10 cases demonstrating increased numbers of IgG4-positive plasma cells.

DISCUSSION AIP is defined as a mixed inflammatory cell infiltrate centered

on the pancreatic ducts with an associated venulitis.

It is important to distinguish between pancreatic ductal carcinoma and AIP since they have overlapping clinical and radiological features.

The most common cytomorphological findings of AIP included cellular stromal fragments and inflammatory cells, present either within the stroma or in the background.

In this study, pancreatic FNA of AIP most frequently led to an ‘atypical’ cytopathologic interpretation.

The presence of significant epithelial atypia was often limited to a few or scattered groups of ductal cells.

This is due to the surrounding inflammatory and fibrotic process.

In the cases available for review ,the most common findings were hypocellular background lacking red blood cells.

Fragments of fibrous tissue and focally atypical ductal epithelium were frequently seen.

Inflammatory cells were not observed in majority of cases.

AIP is considered one of several manifestations of systemic IgG4- related disease.

They may affect diverse organs including: Bile duct Salivary gland Lacrimal gland Retroperitoneum Aorta Lung Kidney

Extrapancreatic manifestations, including sclerosing cholangitis, appear to be more commonly associated with the lobulocentric pattern of AIP.

Also, majority of the accompanying biliary cytology specimens were found to be benign.

Elevation of serum IgG4 is invariably associated with AIP, thus immunolabeling for IgG-positive plasma cells on histologic sections has become a key diagnostic tool.

Based on the result of the present study, this ancillary technique may prove most useful in cases with worrisome but inconclusive atypia or scant cytologic material.

In such cases performing IgG4 immunolabeling on the cell block material may demonstrate elevated IgG4 – positive plasma cells, providing an important clue to correct diagnosis and altering the patient’s treatment course.