Subcutaneous zygomycosis is an uncommon chronic deep fungal infection caused by the group of fungi belonging to the order Entomophthorales predominantly by Basidiobolus ranarum and Conidiobolus coronatus. It is a saprophytic fungus found in soil and plant debris and also isolated from the vegetation contaminated with feces of lizards, frogs, and reptiles. The mode of transmission is by implantation through trauma, insect bite, or by inhalation of fungal spores.
Herein, we report a case of subcutaneous zygomycoses in an immunocompetent child.
A 17-month-old female child presented to the dermatology outpatient department with asymptomatic swelling of left half of the face and neck for 6 months. It was insidious in onset, started as papular lesion on the left side of the neck and gradually progressed to involve left side of the face. Her parents denied any history of trauma, insect bite, fever, cough, or any other systemic complaints. The swelling progressed despite aggressive management in the form of systemic antibiotics, anti-tubercular drugs from various hospitals. Previous fine-needle aspiration cytology was suggestive of suppurative granulomas and biopsy was indicative of eosinophilic panniculitis. Complete re-evaluation and examination was undertaken.
On examination, a solitary, ill-defined, irregularly shaped swelling of size 10 cm × 8 cm approximately extending from the left orbit to left clavicle was present. Overlying skin was erythematous, tense, shiny, scaly with an oval scar surmounted by brownish crust (indicating previous biopsy) [Figure 1a-c]. On palpation, it was warm, nontender, nonpulsatile, nonfluctuant, and freely mobile over underlying structures with a positive finger insinuation test. Regional group of lymph nodes could not be assessed, other lymph nodes were unremarkable. Mucosa and epidermal appendages were normal. There were no other systemic findings.
Laboratory investigations including total leukocyte count (17000/mm3) and total eosinophil count (900/mm3) were raised. All other laboratory parameters were within the normal limits. Serological tests for HIV and HBs Ag were nonreactive.
Radiological investigations including magnetic resonance imaging revealed a large extensive, infiltrative, heterogeneously enhancing soft-tissue lesion seen involving the skin and subcutaneous plane of left buccal region appearing hypo-intense on T2WI and iso-intense on T1WI. No vascular channels were noted on Doppler studies. X-ray of the skull and chest was normal.
Histopathology revealed dense infiltrate of eosinophils, small cluster of epithelioid cells, foci of necrosis with few broad aseptate fungal hyphae surrounded by eosinophilic material [Figure 2a and b].
Microbiological evaluation for pyogenic organism and fungus was done. Fungal culture on Sabouraud dextrose agar (SDA) media revealed furrowed and folded colonies with brownish pigment and waxy texture [Figure 3a-c]. Lactophenol cotton blue mount test showed aseptate large hyphae with round, smooth, thick-walled zygospores with conjugation beaks [Figures 4 and 5]. Pyogenic culture was sterile.
On the basis of clinical examination and laboratory findings, the diagnosis of subcutaneous zygomycosis was made.
The class Zygomycetes includes two fungal orders, i.e., Mucorales and Entomophthorales. Mucorales affects immunocompromised individuals, whereas entomophthorales affect the immunocompetent individuals, causing principally chronic infection of the subcutaneous tissue.
Entomophthorales is a tropical fungus chiefly encountered in East and West Africa, Indonesia, and India. It is transmitted mainly by minor trauma, insect bite, and inhalation of fungal spores. It includes two genera Conidiobolus and basidiobolus[Table 1]. The important species include C. coronatus, C. incongruous, B. ranarum, and B. haptosporus.
Basidiobolus mainly affects children in a bathing suit fashion, i.e. buttocks, thighs, and perineum. However, the face and neck were affected in this case that is interesting and contradictory to the classical form.
Thermo tolerance serves as an important virulence factor, allowing it to survive in febrile patients.
It clinically manifests as smooth, round, well defined, painless firm to hard subcutaneous mass that is nonadherent to underlying structures. The border of the nodule can be raised up by inserting fingers underneath it (finger insinuation test) which is the diagnostic clinical feature and was present in this case also. The spread is contiguous in subcutaneous planes. Overlying skin may be tense, edematous, desquamating, and hyperpigmented or normal. Spontaneous resolution may occur after a long period.
It is important to differentiate subcutaneous zygomycosis from other subcutaneous fungal infections, eosinophilic fasciitis (presents as woody swelling of hands and feet), panniculitis (manifest as erythematous tender nodules mainly over limbs), subcutaneous lymphoma, and other granulomatous conditions such as tuberculosis, localized filarial elephantiasis, scleredema, and scleroderma.
Histopathology shows inflammatory granulomatous reaction with a predominant mononuclear cell infiltrate consisting of lymphocytes, histiocytosis, and multinucleate giant cells. Irregular branching with broad thin-walled hyphae surrounded by eosinophilic material is known as Splendore-Hoeppli phenomenon [Figure 2a and b]. Other signs such as invasion of blood vessels, necrosis, and tissue infarction are absent.
For fungal hyphae periodic acid-schiff and Gomori-Grocott methenamine silver stains are used [Figure 6a and b]. Culture on SDA shows flat, furrowed, yellowish to grayish colonies with a waxy texture.
No single drug is considered the treatment of choice and most commonly saturated solution of Potassium Iodide (KI), Itraconazole, Ketoconazole, Amphotericin B and Trimethoprim-sulphamethoxazole have been tried in various combinations with variable success.
In this case after complete thyroid profile, combination of saturated solution of KI (2 drops thrice a day with an increment of 1 drop each until 45 drops thrice a day with continuous monitoring for features of iodism) and itraconazole (5 mg/kg body weight) were given with drastic response within 2 months [Figure 7a and b] followed by drastic improvement in 2 months.
A hard facial swelling not responding to conventional treatment for pyogenic infections or to anti-tubercular drugs should be worked up for deep fungal infections such as subcutaneous zygomycosis. Potassium Iodide, a traditional and economic but a wonderful drug should be used more often in the today's scenario of resistant fungal cases, although a combination of drugs can yield a better result as evident in our case.
Declaration of consent
The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children 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
There are no conflicts of interest.
The authors would like to thank the Department of Pathology and Microbiology SMS Medical College, Jaipur, India.
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