TOP DERMATOLOGIST PROVED THE VALIDITY OF FINE NEEDLE ASPIRATION CYTOLOGY AS A DIAGNOSTIC TOOL IN SCROFULODERMA

Top dermatologist proved the Validity of Fine Needle Aspiration Cytology as a Diagnostic Tool in Scrofuloderma. This study was published in ‘International Journal of Pathology; 2008; 6(2): 79-82’

Ambreen Qadeer andIkamullah Khan

Department of Dermatology, Pakistan Institute of Medical Science, Islamabad

Background: Scrofulderma has no specific Diagnostic test. Skin biopsy taken for histopathology only reveals a sinus tract and demonstration of organism in skin biopsies by ZN stain in culture in time consuming and often unrewarding, especially in paucibacillary disease. Find needle aspiration cytology (FNAC) is an economical, dependable, quick and cost effective tool for an early diagnosis compared to biopsy studies.

Aim: the present study was undertaken to assess the utility of (FNAC) of lesions in diagnosis of Scrofuloderma.

Method: FNAC of lesions of scrofuloderma and lymph nodes draining the lesions was carried out followed by skin biopsy in 15 fifteen patients of clinically suspected cases of scrofuloderma.

Observation: Smears ravealed epithelioid cell granulomas with mononuclear cell infiltrate over a necrotic background. Also seen were scattered giants cell. Histopathology studies of skin biopsies revealed epithelioid cell granulomas and Langhans’ gaint cell 11 out of 15 biopsies were also negative for AFB by ZN stain and culture. All the patient responded well to standard antituberculous regimen.

Conclusion: FNAC of lymph nodes in cases of cutaneous Tuberculosis is a useful procedure that helps in arriving at a diagnosis within a reasonable time frame.

Keywords: FNAC, Lymph node, Cutaneous Tuberculosis , Scrofuloderma

Introduction

The diagnosis of tuberculosis resets mainly on the demonstration of AFB in Ziehl-Neelsen Stained smears/biopsies or by positive culture. As the organism is very slow growing, confirmation of the diagnosis may take several weeks, thus delaying the institutions of therapy. Although culture is the gold standard for the diagnosis of tuberculosis, its major drawback besides slow growth is slow sensitivity. This sensitivity particularly low in cutaneous tuberculosis, due to the paucity of organisms in the sin is most types of cutaneous lesion especially scrofuloderma. Even PCR is not that reliable in paucibacillary disease like scrofuloderma.¹

In majority of peripheral centers in our country, the facilities for histopathological diagnosis and for culture of the organisms are lacking. Hence, it modality by adopted to confirm the diagnosis.

Cytology is now used in clinics and hospitals throughout the world as first line of investigations of the patients suspected of having lymphadenopathy. However, interest in cutaneous cytology has been limited. Cytologic examination is simple and efficient, does not require local anesthesia, saves time, provides a rapid diagnosis, and can be considered, in experienced hands, reliable for the confirmation of tuberculosis.³

Find needle aspiration cytology (FNAC) entails using a narrow guage (25-22G) needle to collect a sample of a lesion for microscopic examination. Published series of FNAC show a wide variation in diagnostic accuracy and complication rates. This reflects the expertise of those taking and examining the samples. The trauma and risk of biopsy are greater than for fine needle aspiration.⁴

FNAC of the lesions of scrofuloderma, in our study, revealed granulomatous lesions, recognized by the presence of clusters of epithelioid cells scattered throughout the smear with or with caseous necrosis. The epithelioid cells were elongated, often semi-lunar with a fine granular nuclear chromatin. Langhans giants cells were seen either in association with epithelioid cells or singly, against an inflammatory background of neutrophils. This much evidence, in our opinion, is sufficient to make a confident diagnosis and institute anti-tuberculous therapy. The objective of this study was to determine validity of fine needle aspiration cytology in the diagnosis of the scrofulodrema .

Material and Methods

This cross-sectional  (validation) study was conducted in the out patients department of Dermatology of Pakistan Institute of Medical Sciences, Islamabad, which is a tertiary care hospital, over a period of six months.

Patients were selected by purposive (non-probability) sampling. Inclusion criteria were as follows:

Cytological specimens were obtained by fine needle aspiration cytology directly from the lesion.

Histopathology specimen was obtained by either incisional or excisional biopsy.

Staining was done by the standard Hematoxylin and Eosin stains.

Patients who had received any kind of treatment for the disease/lesion were excluded from the study. Also excluded were those taking anticoagulants or having allergies to local anaesthesia.

After obtaining informed consent of the patients and with permission from the hospital ethical committee, patients’ demographics were recorded in the performa.

Fine needle aspiration were performed using a narrow gauge (22G) needle to collect sample of a lesion for microscopic examination from at least three different points and at three different depths under strict aseptic technique. Each specimen was considered independently even if taken from the same patient.

Histopathological specimens were obtained with a 4-mm punch biopsy or excision under local anesthesia. The biopsies were fixed in 10% formaldehyde, routinely processed, and embedded in paraffin. Sections were stained with hematoxylin and eosin.

The data was analyzed in SPSS version 13. Numerical variables (age, duration) were reported as mean and standard deviation. Categorical data was presented as Frequency and percentages.

Of the 15 patients included in the study based on clinical diagnosis, 13 were confirmed as scrofuloderma while 1 was found to be deep mycosis on histopathology while 1 in the gluteal region in a male who was a recently diagnosed as a case of pulmonary tuberculosis and referred for a discharging sinus in the gluteal region was confirmed to be of pilonidal sinus.

                                            Figure 4: A hostopathology sample showing Multiple Giant Cells and Granulomas

All 13 patients diagnosed on the basis of Granulomas and typical cells on FNAC responded to the standard Anti Tuberculous Treatment.

Discussion

Tuberculosis is an important world health problem with an estimated 8 million new cases and 3 million deaths every year. The resurgence of this disease, not only in Third World Countries but also in the developed world, may be attributed to the growing number of immunocompromised human immunodeficiency virus (HIV)-infected individuals. Moreover, HIV-infected individuals often present with an atypical clinical picture, which leads to delay in diagnosis and prolonged infectivity.¹

There are several  morphological patterns of cutaneous tuberculosis, some due to the causative organism itself and other due to an active disease elsewhere in the body. Scrofuloderma is associated with skin involvement secondary to an underlying focus, usually a lymph node or bone, but even structures like the eye have been reported to be involved in ocular scrofuloderma.

There is no definite diagnostic test for scrofuloderma. A skin biopsy taken for histopathology may only reveal a sinus tract and debris as the only clue to an non-specific inflammatory process. A lymph node biopsy or underlying  bone biopsy is diagnostic in most cases but in an invasive procedure requiring proper surgical facility.⁶

The diagnoses of scrofuloderma usually rests on the response to a trial of anti-tubercular therapy which involves all the pharmacological hazards of long tern treatment with multiple drugs. Even the therapeutic trial may sometime fail due to the increasing incidence of multi-drug resistance tuberculosis which further complicates the diagnosis.

Attempt to culture the mycobecteria from the lesions of scrofuloderma are often unsuccessful  due to the puacibacillary nature of this variant of tuberculosis. Polymerase chain reaction shows promising results even in paucibacillary disease but is expensive and highly sophisticated technique requiring a proper setup which is not readily available. A needle aspiration biopsy is safer and less traumatic then an open surgical biopsy and significant complications are usually rare, depending on the body site. The diagnostic importance of FNAC of lymph nodes in tuberculous lymphadenitis has been highlighted by several workers.² FNAC has been employed in the diagnosis of tuberculosis of other tissues like breast etc.

Other authors demonstrated granulomas by FNAC in tuberculous mastitis and held that granulomatous mastitis must be considered even in the absence of AFB. The finding of epitheloid cell granulomas with a mononuclear cell infiltrate and scattered giant cells in pathognomonic and consistent with work reported by others.

11 out of the 13 smears in the present study were negative for AFB by ZN stain, while varying degrees of positivity are reported by other authors. It has been opined that absence of AFB in smears showing an otherwise characteristic cytological picture should not weigh against the diagnosis of tuberculosis.

Although the sample size in this study was small it does not weigh down prevalence of cutaneous tuberculosis in our part of the world as the duration of the study was only 6 months and scrofuloderma represents only a small fraction of its cutaneous presentations. In our opinion FNAC examination is a simple, and a relatively painless and less cumbersome procedure can be adopted to serve as an effective adjuvant in arriving at a diagnosis for as it can be carried out as an O.P.D procedure and preparation of the smears can be carried out in the laboratories even at the peripheral hospitals.

References

1. K. Arora, B, Kumar * and S. Sehgal. Development of a polymerase chain reaction dot-blotting system for detecting cutaneous tuberculosis.
2. Padmavathy Lanka, Lakshmana Rao Lanka and B. Krishnaswamy: Role of fine needle aspiration cytology of lymph nodes in the diagnosis of cutaneous tuberculosis; Indian J Tuberc 2004; 51:131-135.
3. Kumar GL, Singhi MK. Tzanck smear: A useful Diagnostic tool. Indian J Dermatol Venereol Leprol 2005; 71:295-9.
4. Christensen E, Bofin A, Guomundsdottir I, Skogvoll E. Cytological diagnosis of basal cell carcinoma and actinic keratosis, using Papanicolaou and May-Grunwald-Giemsa stained cuteneous tissue smear. Cytopathology 2007; 1365-2303.
5. Suavasini Sharma, Monica Juneja, Ravindra Kumar Saran; Bilateral ocular scrofuloderma with orbital tuberculosis; Indian J Pediatr 2006; 73(4): 361-363.
6. Paller A S, Wolff K, Lowella A, David J, Goldsmith L, Katz S l, Gilchrest B; Fitzpatrick’s Text book of Dermatology: 2008; vol 2; 1770-72.                                                                                      Prof. Dr. Ikram Ullah Khan For correspondence, Department of Dermatology, PIMS, Islamabad