Cytological diagnosis of chromoblastomycosis.

The diagnosis of chromoblastomycosis requires the demonstration of ‘sclerotic’ or ‘muriform’ bodies in the clinical material including scrape smear or fine needle aspiration cytology (FNAC) smears or histopathology of biopsied material. However, it is very difficult to diagnose in cytology smears unless there is strong clinical suspicion because most lesions present as verrucous lesions confused for neoplastic condition. Even with strong clinical suspicion diagnosis in FNA smears is very challenging as the most aspirates are hemorrhagic. The diagnosis of chromoblastomycosis is challenging and usually missed unless the pathologist has awareness of the lesion and characteristic morphology of sclerotic bodies. However, identification of the specific etiologic agents requires culture studies.[1] Review of literature shows paucity of case reports of cytological diagnosis of chromoblastomycosis.[2]

A 24-year-old male patient presented with an ulcerated verrucous lesion over the right great toe of 3 years duration associated with pain and itching [Figure 1a]. To begin with the lesion was small and gradually progressed to the present size and became ulcerated. There was no history of trauma. On local examination showed a verrucous lesion measuring 1.5 × 1.0 cm with crusting [Figure 1a].

Figure 1

Gross feature showing (a) cauliflower-like growth with ulceration (thick black arrow head). (b) Fine needle aspiration smears showing brown ‘sclerotic body’ (thin black arrow head (H and E, ×400), (c) Rouleaux formation of red blood cells (thin black arrow head) (H and E, ×400), and (d) equatorial septation of ‘sclerotic body’ (thin black arrow head) and a neutrophil (thick black arrow head) (H and E, ×1000)

FNAC smears showed hemorrhagic background with scattered lymphocytes, plasma cells, rouleaux of erythrocytes, amidst there were scattered brown colored round structures (sclerotic bodies) slightly larger than lymphocytes [Figures 1b and c]. These structures showed equatorial septation [Figure 1d].

Histopathological examination of the specimen revealed pseudoepitheliomatous hyperplasia, microabscesses with characteristic ‘sclerotic’ bodies, and giant cell response [Figure 2].

Figure 2

(a) Histopathology showing pseudoepitheliomatous hyperplasia, (b) giant cell granulomatous response to sclerotic bodies which are inside the giant cells (Heamatoxylin and eosin, ×40) (c) microabscesses (Heamatoxylin and eosin, ×40), (d) Sclerotic bodies (Fontana-Masson, ×100)

The term ‘chromoblastomycosis’ is exclusively used for those fungal lesions which characteristically produced ‘sclerotic’ bodies caused by dematiaceous fungi, and belong to the group of ‘phaeohyphomycosis’.[1234] The etiologic agents belong to species Fonsecea, Cladosporium, and Rhinocladiella.[1234] Most of the etiologic agents produce only localized disease restricted to skin and subcutaneous tissue. High index of suspicion and prompt laboratory diagnosis will help in initiation of therapy at an early stage and isolation of specific etiologic agent by culture may help prevent the latent complications.[1234]

Review of literature showed only two case reports of cytodiagnosis of chromoblastomycosis.[25] It reflects that many cases are missed cytologically (as well as histologically) due to lack of ‘clinical suspicion’. Frequently, the aspiration smears show mixed inflammatory cells and scattered fungal sclerotic bodies. The sclerotic bodies look orange to reddish brown round to polyhedral, about the size of red cells (approximately 5-8 μm), show mature thick wall (just like outer border of copper penny), and characteristic intracellular septations. Though the ‘splitting’ or ‘septation’ in one or two planes is pathognomonic for the organism, not all organisms exhibit septations. Red cells are pinkish orange and usually form rouleaux, whereas sclerotic bodies are pale brown or brownish yellow color and usually occur in singles in aspiration smears (occurrence in chains is a characteristic feature in tissue sections). Though septation is not a consistent feature, if present is a characteristic feature of chromoblastomycosis.[256]

It is really challenging for pathologist in FNA smears when (1) the organisms are sparse, (2) the lesion is not fully evolved (as in early ulcer/plaque stage), and (3) there is no ‘clinical suspicion’ in the request form.[256]

Major drawback in the cytological diagnosis of chromoblastomycosis is the fact that the diagnosis is likely to be missed due to low density of diagnostic sclerotic bodies in the aspirates especially in fully evolved cases showing cauliflower-like growth.[256]

In early lesions the clinical suspicion is difficult and the organisms may be in good numbers including both yeast forms and rare hyphal forms. The tissue response is mainly mixed inflammatory cells infiltration tending to form microabscesses and the responses like fibrosis and epithelial hyperplasia are less pronounced and hence yield by needle aspiration is likely to be more.[134]

As the lesion evolves the tissue response like fibrosis, epithelial hyperplasia and granulomatous response will be more pronounced and grossly the lesion assumes characteristic cauliflower like growth and confused for malignancy. As the lesion evolves, the organisms become sparse due to 1) degeneration of sclerotic bodies which loose morphologic characteristics 2) organisms undergo adoptive changes and become tougher and harder ‘sclerotic’ bodies which may elicit strong fibrotic response, granulomatous response, or dystrophic calcification and hence gets themselves entangled in them. So chances of yield of diagnostic ‘sclerotic bodies’ in aspiration smears are less in fully evolved cases and the diagnosis is usually missed. In that case the histopathology is the gold standard in its diagnosis.[256]

To conclude, the diagnosis of chromoblastomycosis in FNA smears is really challenging due to 1) lack of clinical suspicion and 2) low density of organisms in fully evolved lesions with hyperplastic, fibrotic, and granulomatous tissue response. Histopathology is the gold standard in fully evolved lesions.