Presentation
Patient with past medical history of HIV presents to the Infectious Diseases Clinic for evaluation of a mass in the right frontoparietal scalp.
Patient Data
The patient is a 40-year-old male with a past medical history of HIV presenting to Infectious Diseases Clinic for a mass in the right frontoparietal scalp. He was found to have a CD4 count of 22 and a viral load of approximately 80,000. Incision and drainage was performed and samples were sent for microbiologic studies which only grew diphtheroids, of unclear relevance to the patient's presentation. The patient's wound was examined by Plastic Surgery and a head CT was performed for concern of bone involvement.
Additionally, a baseline chest x-ray was performed with worrisome findings that prompted further work-up with chest CT.
Head CT scout radiographs show a well marginated, osteolytic lesion in the right frontal/parietal calvarium with an overlying subcutaneous soft tissue defect and surrounding edema.
Non-contrast head CT axial images in brain and bone windows show an approximately 4cm well-marginated osteolytic lesion centered in the right frontoparietal calvarium with associated overlying subcutaneous edema and gas. Additionally, there is a hyperdense epidural fluid collection adjacent to the osteolytic lesion and overlying the right frontal lobe. There is some associated vasogenic edema along the right frontal lobe anteriorly.
MR images demonstrate an enhancing mass centered in the right frontoparietal calvarium with extension into the overlying scalp and underlying frontal lobe with associated epidural and subdural empyemas. There is involvement of the right temporalis muscle and superior sagittal sinus. Additionally, there is a smaller enhancing lesion in the left pons. Both right frontoparietal and left pontine lesions demonstrate increased signal on DWI, more so along the right frontal lobe.
Neurosurgery resected the mass.
Histology:
MACROSCOPIC DESCRIPTION:
Part A - "Scalp lesion": Three gray-tan gelatinous necrotic appearing tissue fragments measuring 0.4 to 0.9 cm in greatest dimension.
Part B - "Scalp lesion": Five portions of gray-tan necrotic appearing tissue measuring 0.2 to 1.1 cm in greatest dimension.
Part C- "Scalp lesion": 8.0 x 7.5 x 3.0 cm in maximum thickness portion of calvarium with attached 7.0 cm pink tan, slightly hemorrhagic lobulated tumor mass. The tumor mass appears to invade and cause a central defect within the calvarium and attached to the underlying bone is a portion of dura with a 5.0 cm lobulated white-tan tumor mass with attached dura.
MICROSCOPIC DESCRIPTION: Sections from all three specimens show sheets of histiocytes, which penetrate thought the calvarium, dura, and into the brain parenchyma. Within the cytoplasm of the macrophages, patchy pale blue, round bodies can be seen. A special stain for calcium shows these bodies to be numerous and morphologically consistent with Michaelis-Gutmann bodies of malakoplakia.
Special stains are negative for fungal organisms, acid-fast and modified acid-fast bacilli, and spirochetes. However, on the GMS stain from the frozen section tissue, there are scattered intracytoplasmic coccobacillary forms suggestive of bacteria.
DIAGNOSIS: Malakoplakia, involving the soft tissue of the scalp, cranial bone, dura, and brain. Special stains for organisms are suggestive of gram-positive coccobacilli.
Frontal and lateral chest radiographs demonstrate right hilar prominence, as well as right lower lung nodules, some of which have features suggestive of cavitation on lateral view.
Chest CT axial images in soft tissue and lung windows demonstrate right hilar adenopathy, as well as an approximately 3.5 cm irregular-shaped, thick walled cavity in the right lower lobe with several surrounding smaller satellite pulmonary nodules, some of which also demonstrate cavitation.
AFB cultures were negative x3.
Immediately prior to the surgical resection of the calvarial mass, the Pulmonary Service performed a bronchoscopy with bronchoalveolar lavage. Bronchoalveolar lavage was negative for fungal organisms, pneumocystis carini, viral effect, and malignancy. Biopsy of endobronchial lesions was also performed during the bronchoscopy which revealed the following:
MACROSCOPIC DESCRIPTION:
"Lung Tissue": Six scant fragments of white-tan tissue and red-brown blood. The largest fragment measures 0.2 cm.
MICROSCOPIC DESCRIPTION: Sections of the biopsy revealed inflamed fibrous tissue with prominent submucosal collections of macrophages. Additional staining of the lung biopsy was performed (calcium/von Kossa), revealing the presence of calcospherites, (Michaelis-Gutmann bodies). Special stains for infectious organisms (GMS, AFB, mucicarmine, Gram stain, Fites, and Steiner) were negative. Neoplastic change was not present.
DIAGNOSIS: Reactive Squamous Metaplasia with Submucosal Proliferation of Macrophages and Acute and Chronic Inflammation, consistent with Malakoplakia.
Fig. 1 - 4: Pathologic findings of Malakoplakia demonstrating sheets of histiocytes containing intracytoplasmic concentric calcifications known as Michaelis-Gutmann bodies. These intracytoplasmic bodies are formed by the fusion and calcification of lysosomes containing digested organisms and are pathognomonic of Malakoplakia.
Case Discussion
The following is a case of malakoplakia with involvement of the scalp, temporalis muscle, skull, dura, cerebrum, superior sagittal sinus, and lung. The patient was treated with resection of the calvarial mass, antibiotics, and HIV therapy with satisfactory results. The lesion seen along the pons was not biopsied, but was presumed to have represented an abscess or additional malakoplakia and was inconsequential to the patient.
Key Learning Points:
Malakoplakia is a rare granulomatous inflammatory disease of unclear etiology. The three main hypotheses implicate specific microorganisms, immunodeficiency, and defective lysosomal function
it most commonly affects the urinary tract, however can potentially occur in any part of the body
histologically, calcified cytoplasmic histiocytic inclusions known as Michaelis-Gutmann bodies are pathgnomonic, but not necessary for the diagnosis
in HIV patients with pulmonary malakoplakia, cavitations have been associated with Rhodococcus equi infection. The laboratory should be alerted of this suspicion, as samples with profuse coccobacillus growth may be discarded as contaminants
cerebral malakoplakia has been associated with herpes infection in children and areas of cerebral infarct in adults
Case co-authors: Dr. David Poage, Dr. Matthew DeVries, Dr. Annelisse Santiago Pintado
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